重庆大学作业与思考题 2

习题及思考题思考题2-1 思考题2-1a图所示体系不发生形状的改变，所以是几何不变体系；图b所示体系会发生双点画线所示的变形，所以是几何可变体系。

上述结论是否正确？为什么？2-2 多余约束是否影响体系的自由度？是否影响体系的计算自由度？是否影响体系的受力和变形状态？2-3 几何不变体系的计算自由度与多余约束个数之间的关系是什么？2-4 几何组成分析中，部件或者约束是否可以重复使用？思考题2-4图示体系中作为约束铰A可以利用几次？链杆CD可以利用几次?2-5 试求思考题2-5图示体系的计算自由度W。

1) 若视①～⑧杆为刚片，则公式W=3m-(3g+2h+r)中，h=？r=？2) 若视③～⑧杆为刚片，则h=？r=？2-6 如思考题2-6图所示，此体系为三刚片由不共线三铰A、B、C相连，组成的体系几何不变，且无多余约束。

此结论是否正确？为什么？2-7 如思考题2-7图所示，三刚片由不共线三铰A、B、C相连，组成的体系几何不变且无多余约束。

此结论是否正确？为什么？2-8 几何常变体系和几何瞬变体系的特点是什么？（试从约束数目、运动方式、受力及变形情况等方面讨论）。

2-9 静定结构的几何特征是什么？力学特性是什么？2-10 超静定结构的几何特征是什么？力学特性是什么？习题2-1是非判断(1)若平面体系的实际自由度为零，则该体系一定为几何不变体系。

( )(2)若平面体系的计算自由度W=0，则该体系一定为无多余约束的几何不变体系。

( )(3)若平面体系的计算自由度W＜0，则该体系为有多余约束的几何不变体系。

( )(4)由三个铰两两相连的三刚片组成几何不变体系且无多余约束。

( )(5)习题2-1(5) 图所示体系去掉二元体CEF后，剩余部分为简支刚架，所以原体系为无多余约束的几何不变体系。

( )(6)习题2-1(6)a图所示体系去掉二元体ABC后，成为习题2-1(6) b图，故原体系是几何可变体系。

( )(7)习题2-1(6)a图所示体系去掉二元体EDF后，成为习题2-1(6) c图，故原体系是几何可变体系。

第二章习题答案2-2 真空中有一长度为l 的细直线，均匀带电，电荷线密度为。

试计算P 点的电场强度：τ（1）P 点位于细直线的中垂线上，距离细直线中点l 远处；（2）P 点位于细直线的延长线上，距离细直线中点l 远处。

解：（1）可以看出，线电荷的场以直线的几何轴线为对称轴，产生的场为轴对称场，因此采用圆柱坐标系，令z 轴与线电荷重合，线电荷外一点的电场与方位角无关，这样处取的元电荷φz '，它产生的电场与点电荷产生的场相同，为：z q 'd d τ当R20e R4z E πετ'=d d 其两个分量：（1）θπετρρcos 20R4z e E d dE '=∙=d （2）()θπετsin 20z z R4e E d dE z d '-=-∙=又θρθρtan ',cos ==z R 所以：（3）θθρd dz 2sec '=式（3）分别代入式（1）（2）得：；θρπεθτρd 04dE cos =θρπεθτd sin 0z 4dE -=（4）'sin 'sin cos θρπετθθρπετθρπεθτθρ000004E 22d 2=⎰∴当当‘又（5）2l 42l 2l+='θsin 式（5）代入式（4）得：l55E 00πετρπετρ22=∴当由于对称性，在z 方向 分量互相抵消，故有z E 0=z E ρρρπετe l5e E e E 0z z2E =+=∴ρy图2-2长直线电荷周围的电场为”1 三开到联2（2）建立如图所示的坐标系在x 处取元电荷则它在P 点产生的电场强度为dx dq τ=R20e R4x d E d πετ'=其在x 方向的分量为：20x R 4x d dE πετ'=又 xl R -=2020x x l 4x d R4x d dE )-(''='=∴πετπετ()l3x l 4x l 4x d E 02l 2l 2l 2l 020x πετπετπετ='-⨯=''=--⎰∴∴∴////1)-( x 0x x x e l3e E Eπετ==∴2-3真空中有一密度为的无限长线电荷沿y 轴放置，另有密度分别为和m C n /2π2/1.0m C n 的无限大带电平面分别位于z=3m 和z=-4m 处。

第2章习题答案一、暂态作业1. 为何要对同步发电机的基本电压方程组及磁链方程组进行派克变换？ 答：由于同步发电机的定子、转子之间存在相对运动，定转子各个绕组的磁路会发生周期性的变化，故其电感系数（自感和互感）或为1倍或为2倍转子角θ的周期函数（θ本身是时间的三角周期函数），故磁链电压方程是一组变系数的微分方程，求解非常困难。

因此，通过对同步发电机基本的电压及磁链方程组进行派克变换，可把变系数微分方程变换为常系数微分方程。

2. 无阻尼绕组同步发电机突然三相短路时，定子和转子电流中出现了哪些分量？其中哪些部分是衰减的？各按什么时间常数衰减？试用磁链守恒原理说明它们是如何产生的？答：无阻尼绕组同步发电机突然三相短路时，定子电流中出现的分量包含： a) 基频交流分量(含强制分量和自由分量)，基频自由分量的衰减时间常数为T d ’ 。

b) 直流分量（自由分量），其衰减时间常数为T a 。

c) 倍频交流分量（若d 、q 磁阻相等，无此量），其衰减时间常数为T a 。

转子电流中出现的分量包含：a) 直流分量(含强制分量和自由分量)，自由分量的衰减时间常数为T d ’ 。

b) 基频分量（自由分量），其衰减时间常数为T a 。

产生原因简要说明：1)三相短路瞬间，由于定子回路阻抗减小，定子电流突然增大，电枢反应使得转子f 绕组中磁链突然增大，f 绕组为保持磁链守恒，将增加一个自由直流分量，并在定子回路中感应基频交流，最后定子基频分量与转子直流分量达到相对平衡（其中的自由分量要衰减为0）。

2）同样，定子绕组为保持磁链守恒，将产生一脉动直流分量（脉动是由于d 、q 不对称），该脉动直流可分解为恒定直流以及倍频交流，并在转子中感应出基频交流分量。

这些量均为自由分量，最后衰减为0。

3. 有阻尼绕组同步发电机突然三相短路时，定子和转子电流中出现了哪些分量？其中哪些部分是衰减的？各按什么时间常数衰减？答：有阻尼绕组同步发电机突然三相短路时，定子电流和转子电流中出现的分量与无阻尼绕组的情况相同。

一、判断题（共20题、共40分）1.使用单位荷载法计算计算位移时,是适用了虚力原理。

正确错误2.两端同支等截面直杆的转角位移方程表达的是三个独立的杆端位移和三个杆端力之间的函数变换关系。

正确错误3.力法基本方程实质是静力平衡方程。

正确错误4.频率方程，为关于w的一元n次方程（n为体系的动力自由度）。

正确错误5.图示体系中的I、II两部分为较结三角形。

正确荷载作用下的梁和刚架中,位移的主要贡献是弯曲变形，通常剪切变形和轴向变形可以忽略不i+o正确错误7.平面一般力系的平衡方程一定可以求解出三个未知量。

正确错误8.两个弯矩图都是非直线图形时,图形相乘法无法直接适用。

正确错误9.图示两弯矩图（对应日为常数），图乘结果为。

正确错误10.力法基本方程中，主系数可能等于零。

正确钱结点可以承受和传递所有类型的内力。

正确错误12.构件抗侧刚度系数越大，其承受的剪力值也就相对越大。

正确错误13.虚位移原理等价于体系的真实平衡条件。

正确错误14.刚体或刚片也可以写作钢体或钢片，是指用钢材制成的物体。

正确错误15.若已知体系运动的初速度（初位移为零），质点的运动规则应表达为正弦函数。

正确错误16.几何瞬变体系不能用作结构的原因是，这类体系在有限的外力作用下可能产生极大的内力。

错误17.钢筋混凝土现浇结点在计算简图中一定都简化成刚结点。

正确错误18.虚功互等定理表明：一个线弹性结构，第一状态的外力在第二状态的位移上所做的外力虚功（W12）,等于第二状态的外力在第一状态的位移上所做的外力虚功（W21）。

正确错误19.若解耦成功，在每一广义自由度上，体系作单频振动。

正确错误20.位移计算公式5.4.1-1只适用于小变形状态。

正确错误二、单项选择题（共20题、共60分）1.下列关于三钱拱或相当简支梁说法中，正确的是（）。

A、任意荷载作用下，三钱拱的弯矩都等于相当简支梁对应截面弯矩减去水平反力与该截面高之三钱拱与相当简支梁相比，具有弯矩和剪力减小，而轴力增大的特点c、三钱拱的内力与相当简支梁的轴力相关D、三较拱的水平推力与其自身（或相当简支梁）的跨度成反比2.国家大剧院（北京）属于（）结构。

研究生课程考核试卷科目：高等流体力学教师：何川姓名：苗闪闪学号：20111002060专业：动力工程及工程热物理类别：学术考生成绩：卷面成绩平时成绩课程综合成绩阅卷评语：阅卷教师（签名）重庆大学研究生院制四、设的气体以的速度以零攻角的速度定常绕流长度为的大平板，试用数值解讨论边界层内的流动规律。

解：设以匀速U运动的流体沿切线方向绕过一静止平板，由于流体的粘性作用，板面上的流体流速被降为零，板壁附近极薄区域的流体沿板的法向存在很大的速度梯度，该区域被称为流动边界层。

，为大雷诺数绕流。

沿板面取x坐标，板的发现方向取y坐标舍边界层的厚度为δ=δ(x)，因厚度很薄，既有。

YV ∞x根据问题的特性，忽略质量力，边界层内的速度矢量,压强，流体力学基本方程具体化为：C.E. (4.1) M.E. (4.2)(4.3)下面，应数量级比较的方法分析方程中各项的数量级关系。

首先，选特征参数U、L，奖方程组中个变物无量纲化，并在无量纲化过程中注意使用各无量纲变量的取值范围为(0，1)或取1的数量级（记作(~1)）。

即令：注：大雷诺数流动时，压力采用流动造成的动压作为参照具有相当的数量级关系。

将各无量纲变量代入式（4.1），并比较其各项的数量级关系，有：将各无量纲变量代入式（4.2），并比较其各项的数量级关系，有：1将各无量纲变量代入式（4.3），并比较其各项的数量级关系，有：1根据物理依据和工程事实，在连续型方程中，认为A=B；在x方向的大量方程中，去掉数量级较低的第一项，保留第二项，即边界层中的粘性作用，认为该项于压力梯度项具有相同的数量级，则有；分析y方向的动量方程，对流项与粘性扩散项具有相同的数量级，而压力梯度项却具有高得多的数量级。

得到简化的近似方程组：C.E. (4.4) M.E. (4.5)(4.6)由式（4.6）可以认为，在任一过断流面上，边界层内各点的压力与其外边界上的流势压力p e相等，即，而边界层外势流区满足这里，即有边界层方程即可表示为C.E. (4.4) M.E. (4.7)对于平板绕流，V e=U=c，则平板然刘的边界层发成可以简化为C.E. (4.4) M.E. (4.8)其定界边界条件为：y=0 : u=0 , v=0(4.9a) y→∞: u=U(4.9b)下面采用无量纲相似性解法。

第一篇土木工程施工技术第一章土石方工程1、土的可松性系数在土方工程中有哪些具体应用？答：土的可松性对确定场地设计标高、土方量的平衡调配、计算运土机具的数量和弃土坑的容积，以及计算填方所需的挖方体积等均有很大影响。

2、试述影响边坡稳定性的因素有哪些？并说明原因？答： a.土质，土质粘聚力越大边坡越稳定，边坡可陡些；b.挖土深度，深度越大，产生滑移土体越重，边坡越不稳定；c.施工期边坡上的荷载，动荷载静荷载增加了边坡的剪应力；d.土的含水率及排水情况，土的含水率越大，土体自重增加土体抗剪强度下降；e.边坡留置时间，留置时间越长边坡越稳定。

3、水泥土墙设计应考虑哪些因素？水泥土搅拌桩施工应注意哪些问题？答：因素：水泥土墙设计应考虑哪些因素：墙背填土的粘聚力和内摩擦角大小、活荷载分布及大小、挡土墙的基底应力大小、挡土墙的结构形式和断面尺寸。

注意问题：水泥土搅拌桩施工中应注意水泥浆配合比及搅拌速度、水泥浆喷射速率与提升速度的关系及每根桩的水泥浆喷注量，以保证注浆的均匀性与桩身强度。

施工中还应注意控制桩的垂直度以及桩的搭接等，以保证水泥土墙的整体性与抗渗性。

4、基坑土方开挖应遵循什么原则？针对不同的基坑应如何具体贯彻？答：原则; 开槽支撑，先撑后挖，分层开挖，严禁超挖。

开挖到坑底后垫层应随挖随浇。

（1）对于放坡和坑内无内支撑的基坑开挖：应严格分层开挖，当基坑面积较大时，应采取分块开挖，基坑分块开挖应尽可能利用后浇带，按后浇带设置分区，尽量避免基础结构因分块开挖而增设施工缝。

对于重力式水泥土墙，在平面上可采取盆式开挖。

对于土钉墙或桩锚结构，宜采用岛式开挖方法。

土方开挖后不应将土方堆放在坑边。

（2）对于由内支撑的基坑开挖：其土方开挖需要与支撑施工相协调，此外，为便于挖土作业，一般需在第一道支撑上设置栈桥，在支撑下布置小型挖土机。

在土质较好的基坑中，可根据条件设置临时坡道，但临时坡道必须稳定可靠，必要时对坡道下的土体进行加固或设置结构性坡道。

思考与练习二班级：13信管A班学号：20131209021019 姓名：张利红一、通过1-3章的学习，回答以下问题：1.一般情况下对“系统”的定义是什么？请分四个层次解释这个定义？答：定义：系统是指将零散的东西进行有序的整理、编排形成的具有整体性的整体。

系统是由一些相互联系、相互制约的若干组成部分结合而成的、具有特定功能的一个有机整体（集合）。

解释：（1）系统是一个动态和复杂的整体，相互作用结构和功能的单位。

（2）系统是能量、物质、信息流不同要素所构成的。

（3）系统往往由寻求平衡的实体构成，并显示出震荡、混沌或指数行为。

（4）一个整体系统是任何相互依存的集或群暂时的互动部分。

2.系统的特征是什么？并对每个特征举例说明，例如目的性：教育系统的目的是培养人才。

答：（1）整体性：地球系统的整体性是诸多元素构成的一个整体系统。

（2）层次性：人体系统分为不同的层次性分别为细胞,组织,器官,系统,个体。

（3）目的性：教育系统的目的是培养人才。

（4）稳定性：软件系统的稳定性是较长时间内系统运行正常。

（5）自组织性：每个系统都有自己的自我组成部分不是都是一样的。

（6）突变性：电脑的软件系统突然中了病毒。

（7）相似性：系统的基本特征都相似。

3.什么是数据、信息，两者有什么区别和联系？并举例说明日常生活中哪些是数据，哪些是信息？答：两者的联系：数据包含信息，数据加工处理之后得到的对人们用利的数据称为信息。

两者的区别：数据就是数值，也就是我们通过观察、实验或计算得出的结果。

信息：指音讯、消息、通讯系统传输和处理的对象，泛指人类社会传播的一切内容。

举例：数据：数字、文字、图画、声音和活动图象。

信息：我传给a一句话，a经过完善信息后传递给b，b在经过加工传递给别人，这就是信息。

4.信息的特征是什么？并解释战略级、战术级和作业级信息的区别？答：特征：事实性、扩散传输性、共享性、增值性、不完全性、等级性、滞后性。

区别：①战略性决策指有关重大方向性问题的决策，如经营方针、长远计划、新产品试制等；②战术性决策指为了保证战略性决策所需要的人、财、物的准备而进行的决策，如人事调动、资金周转、资源分配等；③日常业务活动决策指为了提高日常工作效率和效益而进行的决策，是着眼于短期和个别方面的，如确定采购批量，处理日常业务中发生的问题等。

答案+我名字2020年春季学期课程作业工程力学（二）第1次工程力学（二）题号一二合计已做/题量0 / 20 0 / 20 0 / 40得分/分值0 / 40 0 / 60 0 / 100一、判断题(共20 题、0 / 40 分)1、粘滞阻尼理论一种近似的阻尼分析模型，其方向恒与质点速度方向相反，表明在运动中阻尼力恒作负功。

正确错误收藏该题2、几何可变体系包括几何常变体系和几何瞬变体系两类。

正确错误收藏该题3、主振型矩阵就是坐标变换矩阵。

正确错误收藏该题4、若解耦成功，在每一广义自由度上，体系作单频振动。

正确错误收藏该题5、力矩分配法只能用于计算仅有结点角位移的体系。

正确错误收藏该题6、简支梁弯矩包络图中的最小弯矩Mmin曲线与移动荷载无关。

正确错误收藏该题7、铰结点处的结点转角，一般不计算入独立的位移法未知量。

正确错误收藏该题8、使用单位荷载法进行超静定结构位移计算时，应保证除单位力外，其余参与平衡的力都作用在原结构的支座约束方向上。

正确错误收藏该题9、如果一个体系可用二元体规则判定其几何组成性质，则无法用二刚片规则判定其几何组成性质。

正确错误收藏该题10、竖向荷载会在转角位移上作虚功。

正确错误收藏该题11、均布荷载作用的起始点和终止点处，弯矩图有尖点。

正确错误收藏该题12、取面积的曲线图形可进行任意拆分,但拆分后每一面积图只能分布杆件的一侧。

正确错误收藏该题13、用力法计算荷载作用下的超静定结构时，解得的多余未知力与结构刚度无关。

由此可知，荷载作用下超静定结构的内力与刚度无关。

正确错误收藏该题14、平面体系的计算自由度不大于其自由度。

正确错误收藏该题15、不随时间变化的荷载称为静荷载，随时间变化的荷载称为动荷载。

正确错误收藏该题16、任意广义坐标变换都不会影响体系的运动频率和相位角。

正确错误收藏该题17、层间剪力为各柱顶剪力之和。

正确错误收藏该题18、若曲线图形面积进行了拆分,对应另一个取高度的直线图形是不能进行拆分的。

一、单项选择题(共30 题、共90 分)得分：69 分1.表面积为的长方体中最大体积为（）。

A、答案++13977 98 885B、C、D、答案错误得分2.幂级数的收敛域为（）A、(−0.5, 0.5]B、{0}C、[−0.5, 0.5]D、(−0.5, 0.5)答案正确得分3求点(1,2,3)到平面的距离是（）。

A、B、C、1D、答案正确得分34.设a= (2,－3,1),b= (1,－1,3),c = (1,－2,0)，则（a+b）×(b +c)等于( )。

A、（0,－1，1）B、（0,1，－1）C、（0,－1，－1）D、（0,1，1）答案正确得分35.函数的二阶偏导数=（）。

A、16xyB、C、D、答案错误得分6.当k =（）时,平面与互相垂直。

A、3B、C、1D、-1答案正确得分37.下列说法正确的是（）。

A、直线和平面之间的夹角范围在B、两直线之间的夹角范围在C、两平面之间的夹角范围在D、两向量之间的夹角范围在答案正确得分38.下列一阶微分方程中哪个不是可分离变量的微分方程（）。

A、B、C、D、答案正确得分39.设，则=（）。

A、B、C、D、答案正确得分310.微分方程的通解是（）。

A、B、C、D、答案正确得分311.函数的极值点是（）。

A、（3，3）B、（0，0）C、（9，0）D、（0，9）答案错误得分12.设是微分方程的解，是微分方程的解，则（）是微分方程的解。

A、B、C、D、答案正确得分313.已知区域D：由x轴，y轴与直线x+y=1所围成，则积分和积分相比有( )。

A、不能比较大小B、C、答案正确得分314.设a为常数，则级数( )A、敛散性与a的值有关B、绝对收敛C、条件收敛D、发散答案正确得分315.幂级数的和函数为（）。

A、B、C、D、答案正确得分316.有且仅有一个间断点的函数是（）。

A、B、C、D、答案正确得分317.下列平面中，垂直于Z轴的是（）。

A、y－z = 1B、x＋y＋z = 0C、z = 4D、5x－6y = 1答案正确得分318.在)处均存在是在处连续的（）条件。

1、《汽轮机原理》课程的内容包括汽轮机的工作原理、变工况特性、强度与振动、调节系统以及凝汽设备。

学完本课程后能运用汽轮机的基础理论，进行汽轮机通流部分热力核算、机组变工况特性分析、经济性分析、主要零部件的强度和振动分析以及调节系统的工作特性分析等。

立足：使用、设计和研究；学习：课堂+资料+习题2．汽轮机有那些用途，我国的汽轮机是如何进行分类的，其型号和型式如何表示？答：主要用作发电用的原动机，也可直接驱动各种泵、风机、压缩机和船舶螺旋桨等。

还可以利用汽轮机的排汽或中间抽汽满足生产和生活上的供热需要。

按做功原理可以可以分为冲动式和反动式汽轮机；按热力过程特性可以分为凝汽式、背压式、调整抽气式和中间再热式汽轮机。

型号表示为三部分：第一部分有汉语拼音表示汽轮机的形式，数字表示汽轮机的容量，即汽轮机的额定功率；第二部分由斜线分隔的数字分别表示新蒸汽参数、再热蒸汽参数、供热蒸汽参数等；第三部分为厂家设计的序号。

3、研究汽轮机原理要用到的基本假设与基本方程：级内蒸汽流动是一维稳定等熵流动，蒸汽品位高，满足连续流动方程，叶栅曲面合理；Gv=cA，vdp+cdc=0,h0+c02/2=h1t+c1t2/2; 对理论计算的结果必须根据实际情况乘以一个比例系数进行修正，比例系数有实验确定。

4、级的组成：汽轮机的级由喷嘴叶珊和与它相配合的动叶珊组成。

喷嘴叶珊是由一系列安装在隔板体上的喷嘴叶片构成，又称静叶珊。

动叶珊是由一系列安装在叶轮外缘上的动叶片构成。

工作原理：当蒸汽通过汽轮机时，首先在喷嘴叶珊中将热能转化为动能，然后在动叶珊中将其动能转变为机械能，使得叶轮和轴转动，从而完成汽轮机利用蒸汽热能做功的任务。

5．汽轮机的喷嘴和动叶流道是何形状，如何判别喷嘴及动叶的流态，如何选用叶型？汽轮机的动静部分之间的间隙：轴向间隙，径向间隙。

为了减少叶顶漏气损失和缩短机组轴向长度，开式轴向长度越小越好，从经济和安全的角度考虑一般取1.5-2.0mm；为了减少动叶顶部漏气，一般在动叶顶部设置径向汽封，一般取0.5-1.5mm，当叶高较大，取较大值。

思考题及答案第1章【1】工程地质问题包括哪几个方面？答：工程地质问题主要包括地质灾害问题，区域稳定性问题，地基沉降变形问题，地基、斜坡或洞室围岩的稳定性问题，渗漏问题等问题。

【2】工程地质学的定义。

答：工程地质学广义的讲是研究地质环境及其保护和利用的科学。

狭义的讲是将地质学的原理运用于解决与工程建设有关的地质问题的一门学科，是岩土工程的重要组成部分。

【3】工程地质学的研究对象是什么？答：工程地质学的研究对象是工程地质条件与人类的工程建筑活动的矛盾。

【4】工程地质条件有哪些？答：工程地质条件是与人类活动有关的各种地质要素的综合，包括地形地貌条件、岩土类型及其工程地质性质、地质结构与构造、水文地质条件、不良地质作用、以及天然建筑材料等六大方面，是一个综合概念。

【5】工程地质学的研究内容包括什么？答：工程地质学研究内容主要包括地球与地貌、岩石与岩体、岩体的地质构造、第四纪堆积物与土的工程性状、地表水与地下水性质、不良地质现象及防治对策和岩土工程地质勘察等内容。

【6】工程地质学的分析方法有哪些？答：工程地质学常用分析方法包括自然地质历史分析法，工程地质建模与计算，工程地质实验与现场试验，工程类比法。

上述4种方法往往是结合在一起的，综合应用才能事半功倍。

第2章[1] 地球的内圈和外圈各分为哪三圈？各圈层的性质如何？各有哪些特点？答：地球的外部层圈有大气圈、水圈和生物圈。

地球的内部层圈包括地壳、地幔和地核。

地壳是莫霍面以上的地球表层。

地壳厚度是变化的，地壳物质的密度一般为2.6-2.9g/cm3，其上部密度较小，向下密度增大。

地壳通常为固态岩石所组成，包括沉积岩、岩浆岩和变质岩三大岩类。

地幔是位于莫霍面之下，古登堡面之上。

体积约占内圈总体积的80％，质量约占内圈总质量的67.8％，主要由固态物质组成。

地核是地球内部古登堡面至地心的部分，其体积占地球总体积的16.2％，质量却占地球总质量的31.3％，地核的密度达9.98-12.5 g/cm3。

Suggested Answers to QuestionsAnnabel Lee1. Who was the prototype of Annabel Lee?There has been a debate for many years over who, if anyone, was the prototype of “Annabel Lee”. Though many women have been suggested, Poe’s wife Virginia Eliza Clemm Poe is one of the more credible candidates: she was the one he loved as a child, and the only one that had been his bride, and the only one that had died. And at the same time, some believed that Annabel Lee was merely the product of Poe’s gloomy imagination and that Annabel Lee was no real person.2. What kind of love is kept in the speaker’s heart?It is really hard to define the love in this poem. It may be the love between lovers. But whatever the love is, it is the love that is stronger than common love and it is beyond what words can express.3. Point out the destructive forces in this poem. How do they act in the great love between the speaker and Annabel Lee?➢The wingéd seraphs of Heaven, wind, highborn kinsmen, demons under the sea.➢The speaker believes that the angels in Heaven envied their love so much that the wind came to make her ill and killed her, and herhighborn kinsmen came to take her away.4. Where does the poem’s mood rise to a high point of defiance?The fifth stanza:But our love it was stronger by far than the loveOf those who were older than we–Of many far wiser than we–And neither the angels in Heaven aboveNor the demons down under the sea,Can ever dissever my soul from the soulOf the beautiful Annabel.5. Why do we find the poem has qualities of a fairy tale?In this poem, we can find many images that usually appear in fairy tales, i.e., demons under the sea and angels in the heaven. The speaker mentions them in the poem and relates them with the death of Annabel Lee. The speaker imagines a kingdom by the sea which also appears frequently in fairy tales.6. The lines of the poem are mainly anapestic. Is this metrical pattern properly used to help reveal the theme?The anapestic shows the sad mood of the speaker. This metrical pattern is in fact a traditional method in the writing of a pathetic poem.A Psalm of Life1. What is the speaker’s view of life? On what is special emphasis laid by him?We should not think about the past and worry about the future. What we should do is to make full use of the present and be optimistic. The poet puts a special emphasis on the action of people. He advocates that people should act and proceed in the present to make life better.2. The lines of the poem are written in trochee. Study the musical effect of this metrical pattern?A trochee is a metrical foot used in formal poetry consisting of a stressed syllable followed by an unstressed one.The lines in trochee usually produce a strong heartbeat and make the reader highly spirited.3. In the poem Longfellow keeps using feminine rhyme in the odd-numbered lines and masculine rhyme in the even-numbered lines. What is the musical effect?Feminine rhymeA rhyme occurring on an unaccented f inal syllable, as in “dining” and “shining” or “motion” and “ocean”. Feminine rhymes are double or disyllabic rhymes and are common in the heroic couplet.Masculine rhymeA rhyme occurring in words of one syllable or in an accented final syllable, such as “light” and “sight” or “arise” and “surprise”.The use of both feminine rhyme and masculine rhyme in the poem make the poem high-sounding and melodious.The Night Has a Thousand Eyes1.What does the speaker mean by saying “the mind has a thousand eyes”?“The mind has a thousand eyes” means the mind can learn things and can express different ideas. Comparing the second stanza with the first one, we can safely infer that the heart is more important than the mind in the speaker’s opinion.2.How does he use metaphors to express his love towards life and his beloved?In the first stanza, the metaphor “the night has a thousand eyes” refers to the twinkling stars. The one eye of the day is the sun. In the second stanza, the metaphor “the mind has a thousand eyes” refers to the minds which can learn and express. T he one eye of the heart is the love. The comparison in the two stanzas is clear - the mind to the heart is what the stars are to the sun, the latter ones are more important than the previous ones.3. Study the poem’s stanzaic form and rhymes.The poem consists of only 2 stanzas of four lines each, and these two stanzas are in parallel structure. This poem has a simple rhyme scheme of A/B/A/B. The first and third lines rhyme with each other while the second and fourth lines rhyme.I Died for Beauty1. This poem may have derived its idea from Keat’s famous line: “Beauty is truth, truth beauty”. Do you think the two are closely related?“Beauty is Truth, Truth Beauty” is a quotation from Keats’s poem “Ode on a Grecian Urn”. In Dickinson’s poem she adopts Keats’s romantic idea of truth and beauty. She imagines that two people are buried in “adjoining” rooms. Though they die for different reasons, they treat each other as “brethren”and “kinsmen”. These descriptions can give us an impression that they are similar but not identical.It is understandable that sometimes, the truth is not as beautiful as we have expected.2. Study the half rhymes in this poem.Half rhyme is also called slant rhyme, near rhyme, oblique rhyme, off rhyme, or imperfect rhyme. It means the final consonants of stressed syllables agree but the vowel sounds do not match. It was only used occasionally in English verse until the late 19th century, when Emily Dickinson and G. M. Hopkins made frequent use of it. In the 20th century half rhyme was adopted widely by English poets.3. What can you imply from the last stanza?In the last stanza, the two neighbours do not talk anymore as the moss “reached” their “lips” and “covered up” their “names”. With this image, the weakness of human beings is shown, because all will be forgotten and death conquers all.Still I Rise1.How do you understand the “you” in this poem?“You” represent those who repress the black in general.“You” treat those blacks as an inferior race and make them suffer.2. How do you understand the “I” in this poem?Here, as the speaker of the poem, “I” have a close relationship with the poet herself. It seems that Maya Angelou describes her own personal feelings in the poem. As a member of the black race, she describes struggles faced by black people or women or any submerged group, and she also tells us her own rise above her painful past.3. What is the tone of this poem?The tone of the poem is encouraging, inspiring, optimistic and passionate.Ah, Are You Digging on My Grave1.The dialogue between two contrasting voices is intended to create irony. To whomdo the voices belong?The first speaker is a dead woman, and the second speaker is her little dog.2. Why is the identity of the second speaker not immediately revealed?The dead woman believes that someone she loved or hated is there at her grave: her husband, her closest of kin and even her enemy. But to her disappointment, none of them can still remember her at the present. When she knows that it is her dog at her grave, she praises it for its fidelity. However, at last, when the poet reveals the second speaker, he really prepares a surprising ending for the readers.3. What theme gradually emerges as each of the first speaker’s guesses proves false?The central theme of this poem is that no love or hate outlasts death. The poem also reflects the coldness lying in the human relationship.4. Why is it ironical when the first speaker praises “A dog’s fidelity” (Line 30)?Before she realizes it is her dog beside her grave, she thinks it must be someone who really cares and loves her, including her husband, relatives or at least enemies. Unfortunately, it turns out that the result fails her: none of her close human beings cares her. When she finally knows that her pet dog is standing on her grave but has forgotten her, the poem becomes ironical.All the World’s a Stage1. Study the metaphors used in this selection. Are they wise enough?Metaphors in this selection are used skillfully. The speaker wisely compares the transitory human life to a stage where a show is presented and each of us has to play seven roles before descending the stage.These seven roles are also seven vividly-employed metaphors, which can be regarded as the most typical image in one’s lifespan.2. What is the third stage? Why is it a stage of sighs and sad ballads?The third stage is the period of love. It is a stage of sighs and sad ballads because there are more loves lost than loves gained.3. Why does Shakespeare call the last stage “the second childishness”?Shakespeare explained the second childishness as “sans teeth, sans eyes, sans taste, sans everything”. It is the last s tage of life in which man gradually grows into senility when his mental and physical health dramatically deteriorates, just like a withered flower. He cannot look after himself; instead he has to rely on somebody else, namely his children. Like an infant, he loses the ability to be independent, so hefeels insignificant as a weak, old thing.A Narrow Fellow in the Grass1.What theme do you conclude from this poem?“A Narrow Fellow in the Grass” shows the contrast between what appears to be and what really is. Dickinson describes the snake by hinting at what it resembles. In the whole poem, there is a split between what it appears to be and what it actually is.2. Study the metaphors used in this poem. What do they imply?In this poem the poet carefully describes the snake as “a narrow fellow” without direct depiction. Several metaphors are used.3. What effects might be achieved according to your appreciation, when some words in the middle of lines, such as “A narrow Fellow in the Grass”, are capi talized?Capitalized words obviously catch the reader’s attention because they leave a more profound impression on the reader. For example, the word “Fellow” is linked with a human being, and it may have a special meaning when it is capitalized. By capitalizing “Fellow” and “Grass”, the poet may arouse the reader’s curiosity and imagination.In a Station of the Metro1. Why has this little poem been considered a classic of Imagist Poetry?The poem was first published in 1913 and is considered one of the leading poems of the Imagist tradition. Written in a Japanese haiku style, Pound’s process of deletion from thirty lines to only fourteen words typifies the Imagist’s focus on economy of language, precision of imagery and experiment with non-traditional verse forms.2. Compare this Imagist poem and the following two Chinese poems. Which one is better, the English one or the Chinese ones?Open for discussion.Anecdote of the Jar1. The jar stands in contrast to the wilderness. Why is t he wilderness “slovenly”? And why “no longer wild”?The jar symbolizes the human world or the human power. The wilderness refers to the natural world. The wilderness is “slovenly” because it is contrasted against the human world and it has not been rem oulded by human power. However, it is “no longer wild” because “the wilderness rose up to it (the jar)”. It has been reconstructed by man into order.2. What is the theme of this poem?In the poem Stevens describes a Tennessee long before human beings lived there.It is in this free natural world that the poet sees as the stage against which man battles nature for supremacy.3. What does the “jar” in this poem symbolize?The jar in the poem symbolizes the human world or the human power.A Red, Red Rose• 1. What does the rose stand for?• 2. How does the poem’s speaker express his love?• 3. Similes and hyperboles are two major figures of speech used in this lyric.Point them out and state their function here.• 4. Why is the 7th line repeated in the 8th line? Is it monotonous?• 5. What is a ballad? Study the rhyme scheme and metrical pattern of this lyric, and compare it with a ballad.• 1. The rose stands for the poet’s love.• 2. In the first stanza the speaker compares his love to a rose and melody; in the second stanza the speaker uses hyperbole to advocate his strong affection to his love; finally the passionate feeling turns to reality. The feeling rises gradually, but it is very impressive and striking.• 3. The first stanza of the poem is a fine example of the usage of simile. The poet compares his love to a red rose and a sweet melody, which shows the sweetness of the youthful energy and natural beauty of his love.•The third stanza uses hyperboles to emphasize the young man’s strong love for his sweetheart. Even though the seas go dry and the rocks melt, his love could never perish.• 4. It is not monotonous. This method can be regarded as repetition which aims to strengthen the effect and make a smooth transition to the following stanza.• 5. A ballad is a poem that tells a fairly simple story (narrative). It usually has an identifiable, powerful metre and strong rhymes in an ABAB or AABB pattern. Some ballads are also set to music. Some ballads are highly descriptive narratives based on heroism or folklore; some are narratives of suffering and love lost; some just tell a humorous story. In modern music, “ballad” has come to refer to a slow, melodic, emotional song.The Last Rose of Summer• 1. What do the rose and the poet respectively sigh for?• 2. W hat does the poet mean by saying “friendships decay”?• 3. What do the gems stand for?• 1. The rose sighs for i ts loneliness as the last rose of summer and the withering of its companions. The poet signs for the decay of friendship and the death ofhis beloved.• 2. “Friendships decay” is in fact an euphemism of the death of friends.• 3. The gems stand for the true love, which the poet values the most. The poet Moore once met a girl with the name of Lena Angle who encouraged him with his works and they became very close. Although she was said to have fallen in love with him she suddenly disappeared. In his search for her Moore found that she had died just days before. Therefore, the gems may probably refer to this girl.Ode to the West Wind• 1. This ode has a rigid metrical pattern and rhyme scheme. Do they harm the expression of the poet’s passion?• 2. Many run-on lines are used in this ode. Do they help to convey the image of the wild west wind?• 3. Analyze the structure of this ode so as to see its development.• 4. In what sense is the west wind both “destroyer and preserver”?• 5. Whose “new birth” do you think the poet wishes to bring about?• 6. What is the relationship between the west wind and the poet?•7. What does the west wind symbolize in this ode?• 1. E ach of the seven parts of “Ode to the West Wind” contains five stanzas—four three-line stanzas and a two-line couplet, all in iambic pentameter. The rhyme scheme in each part follows a pattern known as terza rima, the three-line rhyme scheme employed by Dante in his Divine Comedy.In the three-line terza rima stanza, the first and third lines rhyme, and the middle line does not; then the end sound of that middle line is employed as the rhyme for the first and third lines in the following stanza. The final couplet rhymes with the middle line of the last three-line stanza. Thus each of the seven parts of “Ode to the West Wind” follows this scheme: ABA BCB CDC DED EE.•The wispy, fluid terza rima of “Ode to the West Wind” finds Shelley takinga long thematic leap beyond the scope of “Hymn to Intellectual Beauty,” andincorporating his own art into his meditation on beauty and the natural world.• 2. The run-on lines in this ode are skillfully used to create the tempestuous image of the west wind.• 3. The poem can be divided in two parts: the first three cantos are about the qualities of the ‘Wind’ and each ends with the invocation ‘Oh hear!’ The last two cantos give a relation between the ‘Wind’ and the speaker. The poem begins with three cantos describing the wind's effects upon earth,air, and ocean. The last two cantos are Shelley speaking directly to the wind, asking for i ts power to lift him like a leaf, a cloud or a wave and make him its companion in its wanderings. He asks the wind to take his thoughts and spread them all over the world. The poem ends with an optimistic note: If winter daysare here then spring is not very far.• 4. Shelley talks of the wind as a "Destroyer and Preserver“. He sees a shift of the clouds which warns of an upcoming storm. He then writes of the mourning song "Of the dying year, to which this closing night/ Will be the dome of a vast sepulchre/ Vaulted with all they congregated might" (23-25). The "closing night“ here is used to mean the final night. Shelley shows how he cannot have transcendence even in an open sky for even the sky is a "dome." The "sepulchre" is a tomb made out of rock and his imagination and the natural world will be locked and "Vaulted" tight. But in following lines Shelley writes how this "sepulchre" will "burst" (28). In that sense, "Vaulted"takes on the meaning of a great leap and even a spring. Shelley seems to use obtuse phrasing to frighten the reader and to show the long breath of the wind.He wants the reader to visualize the "dome" as having a presence like a volcano. And when the "dome" does "burst," it will act as a "Destroyer and Preserver". The use of the words "Black rain and fire and hail..." (28) helps the reader prepare for the apocalyptic climax.• 5. To “quicken a new birth” is to quicken the coming of the spring. Here the spring season is a metaphor for a “spring” of human consciousness, imagination, liberty, or morality—all the things Shelley hoped his art could help to bring about in the human mind.• 6. Shelley asks the wind to be his spirit, and in the same movement he makes it his metaphorical spirit, his poetic faculty, which will play him like a musical instrument, the way the wind strums the leaves of the trees. In this poem, Shelley explicitly links nature with art by finding powerful natural metaphors with which to express his ideas about the power, import, quality, and ultimate effect of aesthetic expression.•7. In this ode, the west wind symbolizes a power of change that flows through history, civilization, and human life itself.S hall I Compare Thee to a Summer’s Day• 1. How does the poet answer the question he puts forth in the first line?• 2. What makes the poet think that “thou” can be immortal and more beautiful than summer?• 3. How is this sonnet structured?• 4. Is this sonnet a strict Shakespearean sonnet?• 1. The poet answers the question directly, “thou art more lovely and more temperate”. And by c omparison, the poet lists some negative things about summer: it is short—“And summer’s lease hath all too short a date”, and sometimes the sun is hot—“Sometime too hot the eye of heaven shines”.However, the beloved has beauty that will last forever, unlike the fleeting beauty of a summer’s day.• 2. In the poet’s point of view, the poet thinks the exterior beauty can’t existlong, as time goes on, this transient beauty will disappear. But the charms of a poem will last forever, no matter what would happen.• 3. “Sonnet 18” is a typical English or Shakespearean sonnet. It consists of three quatrains followed by a couplet, and has the characteristic rhyme scheme: abab cdcd efef gg. The poem carries a volta, or shift in the poem's subject matter, beginning with the third quatrain.• 4. This sonnet is a strict Shakespearean sonnet, also called English sonnet, consisting of three quatrains with the rime scheme ABAB CDCD EFEF and a couplet with the rime GG.How Do I Love Thee• 1. What are the three figures of speech in this sonnet? How are they used?• 2. Use several adjectives to describe the love expressed in this sonnet.• 3. The following poem was a popular song of China’s Han Dynasty (206B.C.-220). Compare it with this sonnet. How do they match in intensity?• 1. The poet uses simile, parallelism and climax in this sonnet. The dominant figure of speech in the poem is parallelism. The repetition of t he words “I love thee” builds rhythm while reinforcing the poet’s love.• 2. Love expressed in this sonnet is passionate, deep, brave, pure, and sacred.• 3. The most striking rhetorical feature of this Chinese poem is hyperbole.Open for discussion.I Hear America Singing• 1. Explain what Whitman is hearing in this poem. What kinds of workers does he name?• 2. Find the adjectives the poet uses in describing the people and their songs.What do they suggest?• 3. What is the theme of the poem?• 4. What is the keynote of the poem?• 5. The poem is just a single sentence. What is the significance?• 1. Whitman is listening to America’s singing—the working songs. He names various kinds of workers in the poem: mechanics, the carpenter, the mason, the boatman, the deckhand, the hatter, the ploughboy, the shoemaker, the woodcutter, the mother, the young wife and the girl. These words conjure images of the working class society. This is the majority of Americans. These people are the ones contributing to America with their productive labor.• 2. The poet uses adjectives like “strong”、“blithe” 、“delicious” and “melodious” to describe the song, and he uses “robust” and “friendly” to describe the people.•Phrases such as "blithe and strong," "delicious singing," and "strong,melodious songs" appeal to the imagination with the strength of men intermingled with the beauty of song.Whitman is articulating his view of America as a group of strong people who are beautiful for the work they perform.• 3. In the poem, the poet envisions a country of people working for the greater good of mankind.These people come together as part of the whole society developing industry and production. Each person has a different occupation, but each job is important. So the poem shows the poet’s ideal of a nation: everyone is working together to create a successful and harmonious civilization.• 4. The keynote of the poem is optimism. Whitman's attitude toward Americans is uplifting and positive. He praises Americans and the hard labor they perform. He sees America as a promising land where each person is unique, but united (line 8 "Each singing what belongs to [her] and to none else”8). He praises the work values and ethics of the American people. He depicts a country of people who work hard, yet through the hard work, they enjoy the fruits of their labors ( line 9 "The day what belongs to the day At night, the party of young fellows, robust, friendly”).• 5. This poem demonstrates typical techniques of Whitman. Although there is no end rhyme, we hear a sense of melody in his chiming repetitions and a rhythm in the length of his lines that substitutes for the metrical pattern we expect in conventional poetry. Line one announces the main metaphor.Individual Americans doing their various jobs are a harmonious chorus of happy, proud, creative workers. The whole poem is one sentence; it can be regarded as a continuous song or chorus.The Negro Speaks of Rivers• 1. Consider the clause “when dawns were young” in Line 5. Does it suggest early human civilization?• 2. Four rivers and one person are mentioned by the Negro speaker. Why?• 3. Consider the tone of the Negro speaker. Is it sad, melancholy, proud, or anything else?• 4. In what way has his soul grown deep like the rivers?•• 1. The Euphrates is considered a cradle of human civilization. The speaker of the poem claims to have "bathed in the Euphrates when dawns were young."Thus the voice begins at the origin of civilization.• 2. The rivers are part of God's body, and participate in his immortality. They are the earthly analogues of eternity: deep, continuous, and mysterious.The speaker and the rivers have become one. The magical transformation of the Mississippi from mud to gold by the sun's radiance is mirrored in the transformation of slaves into free men by Lincoln's Proclamation. As the rivers deepen with time, so does the black man's soul; as the rivers ceaselessly flow,so will the black soul endure.• 3. The speaker feels proud of himself and his ancestors.His soft voice contains a firm faith in man.• 4. The poem t races the movement of black life from the Euphrates and the Nile to the Mississippi. The speaker identifies himself and his blackness with the first human beings. The last line of the poem suggests that the speaker is no longer the same man who “bathed in the Euphrates” and “built [his] hut near the Congo.” He is now a black man who has experienced the pain of slavery and racism and the joy of emancipation movement, and his soul now bears the imprint of these experiences.40-Love• 1. What is suggested in the title? What are the significances of 40 and the hyphen in the title?• 2. How is the poem shaped? Does it suggest the poem’s meaning?• 3. How is it possible that a net will “still be between them”?• 4. Look carefully at the positioning of the words in this poem. What happens to the reader’s eyes as the poem is read?• 1. The title suggests that the content of the poem is about love at the age of 40.The hyphen in the title indicates the hedges between the age and this romantic feeling. "40-Love" is a semantic pun here. It can be understood as "love at 40 years of age“, while on the other hand, it suggests a tennis competition that will soon finish.• 2. The form of the poem seems like a tennis court. The line between the words represents the net of the tennis court, and it's a symbol of alienation. It suggests that the middle-aged couple's marriage is like a tennis match which is lack of suspense. Playing around the net seems to have become a habit, which is lack of vitality.• 3. The poem implies the so-called "mid-life crisis" when the collapse of marriage is easy. As time goes on, the passion has faded, and the marriage life turns to be pale, hence the crisis comes.• 4. At the first sight, it’s easy to find key words like “tennis” and “between”thoug h they are divided. The normal sentence order should be “Middle aged couple playing tennis when the game ends and they go home the net will still be between them.” However, the form of the poem is unusual, so is the sentence order. Poetry variant aims to create a "highlight" effect, increasing the performance of poetry. Variations in the language are used to impress readers, bringing joy to them with vast space left for imagination at the same time. Readers’ eyes jump over the net just as the tennis players do.L(a• 1. What is the connection between what appears inside and outside the parentheses in the poem?• 2. What is the theme of the poem? How does the poem’s shape contribute to its theme?• 3. What are the ways in which E. E. Cummings uses formal elements in the poem to communicate a feeling of loneliness to his readers?• 1. The single leaf falling is a metaphor for both physical and spiritual isolation.Loneliness is like a falling leaf, or the feeling of loneliness is the feeling a man gets when he watches a single leaf falling.• 2. Loneliness is like a falling leaf, or the feeling of loneliness is the feeling a man gets when he watches a single leaf falling. It is easy to think of autumn (fall), the end of the growing season, or the death of the year, because in the autumn of a man's life death is a lonely business. The form of the poem does fosters an attitude of internalization, of drawing attention to itself as an artifact,a work of art.• 3. To begin with, the poem dribbles down the page, at once suggesting the descent of a falling leaf, while also visually resembling the figure "1", or a vertical stroke on a page. The reader's progress is slowed down by the shattered syntax, and the reader's eye is forced into a similar movement as that when watching a descending leaf, both finally coming to a rest on the "ground" ("iness"—the longest and last line). We see that the poem is organized into stanzas of alternating lines of 1-3-1-3-1, whilst the first four lines alternate vowels / consonants, both indicating, perhaps, the twisting motion of the leaf as it falls. The parentheses aid this twisting movement, showing first, descent one way, then another. The downward movement is enhanced by lines 5 ("ll") and 8 ("l"), which can be seen as visually enacting the journey. Without even reading the words, the reader is drawn toward one of the main themes of the poem—that of "one." It is no surprise that this poem was the first poem in Cummings' book 95 Poems and was numbered "I", further impressing the main theme upon the reader. Furthermore, in the original printing of 95 Poems (1958), "l(a" appeared opposite a blank page—thus at once suggesting the loneliness explicit in the poem—while all other poems except the last appeared in twos. The twenty-three characters (including the title) seemed lost, overwhelmed by the white space, and one's eyes are automatically drawn to the fragile construction. Metaphorically, then, the poem enacts the vastness of space and the smallness of man within that space. This has existential undertones and implicitly suggests another theme of the poem—that of death (autumn).。