动词不定式用法与专项练习动词不定式: to+do (高二2016.2)动词不定式由“to + 动词原形”组成，是动词的一种非谓语形式。
动词不定式在句中可充当主语、表语、宾语、定语、状语、宾补、主补。
1. 动词不定式在句中的语法功能：(1)动词不定式（短语）作主语To love is to be loved. 爱别人就是被人爱。
To teach is to give. 教书就是奉献。
*to do和v-ing作主语时的区别:Smoking is a bad habit. (v-ing作主语表示习惯性动作)To stay home on such a cold night is comfortable. (动词不定式作主语表示偶然性或一次性的动作)*不定式作主语和目的状语时的区别。
例如：To get up early does good to one’s health.早起对身体有好处。
（作主语）To get up early, one must go to bed early.为了早起，必须早睡。
（作目的状语）(2) 动词不定式（短语）作宾语I will leave it to you to make the final decision. 我将由你来做最后的决定。
(it作形式宾语) She decided to quit her job at last. 最后，她决定辞职。
*"疑问词 + 动词不定式短语"作宾语：I don't know what to do. 我不知道该怎么办。
The children are learning how to play the game. 孩子们在学做游戏。
例如（NMET2000）：I’ve worked wi th children before, so I know what ____ in my new job.A. expectedB. to expectC. to be expectingD. expects (答案:B)(what to expect在句中作know的宾语，而what作不定式to expect的逻辑宾语。
)（四川09） He told us whether _______ a picnic was still under discussion.A. to haveB. havingC. haveD. had (答案: A)又如：It is said that in Australia there is more land than the government knows ____.A. it what to do withB. what to do it withC. what to do with itD. to do what with it答案是C。
what to do with it作knows的宾语。
*注意:有些动词后面必须跟动名词作宾语，平时要注意区别，进行区分。
*forget, remember, try, regret, mean, stop等动词后既可跟不定式又可跟动名词，须根据其习惯用法和语境进行取舍。
例如（MET91）：— The light in the office is still on.— Oh, I forgot____.A. turning it offB. turn it offC. to turn it offD. having turned it off答案是C。
forget to do意为“忘了做（某事）”，forget doing“忘了做过（某事）”；remember有类似的区别。
类似的还有：try to do“尽力做”，try doing“试着做”；regret to say /tell“很遗憾地说”，regret doing“后悔做了……”；mean to do“意欲/ 想要做”，mean doing“意味着做”；stop to do“停下来做另外的事情”，stop doing“停止正在做的事情”。
(3)动词不定式（短语）作表语The most important thing for the United States to do now is to rescue the wounded.现在，对美国来说，最重要的是抢救伤员。
*注意：在“形容词 + 不定式”结构作表语、宾补和定语时，其中形容词多为表示性质的词，如：easy, hard, good, difficult, interesting等,常常是主动式表被动。
例如：These apples are good to eat. 这些苹果很好吃。
（作表语）I find it difficult to understand. 我发现这很难懂。
（作宾补）He is a man easy to get on with. 他是一个容易相处的人。
(作定语)The box is light enough to carry. 这盒子轻得可带走。
（作表语）The future is hard to tell. 未来很难预测。
（作表语）*注意：All you have to do is (to) finish the job quickly. 如果主语部分有个表示不定式内容的 do, 用作表语的不定式可省略 to。
又如：We had nothing to do but _______ (watch) TV yesterday. (答案: watch)We did nothing but ________ (watch) TV yesterday. (答案: watch)(4) 动词不定式（短语）作宾语补足语。
She asked me to stay here. She encouraged me to work hard.We'd love you to give us a hand. 我们想让你帮个忙。
注意：1)在一些动词后，用作宾语补语的动词不定式符号to 要省略掉。
这类动词包括感官动词以及使役动词，如feel, spot, look at, listen to, observe, see, hear, watch, notice, have, make, let, get 等。
但如果句子为被动语态，动词不定式（短语）为主补时，要带to。
I had John fix my bike. 我让约翰修理我的自行车。
They saw the boy fall suddenly from the tree.-----The boy was seen to fall suddenly from the tree.Paul doesn’t have to be made___________ . He always works hard. (答案:B)A. learnB. to learnC. learnedD. learning辨析：I heard her sing a song in the next room yesterday. (强调听歌的整个过程)（=She was heard to sing a song in the next room yesterday.）I heard her sinning a song when I passed by.(强调动作正在发生)(=She was heard singing a song when I passed by.)*see, hear, notice等的宾语后还可跟现在分词作补语，变成被动语态时仍保留分词的形式，表示正在发生的动作。
例如：The missing boys were last seen ____ near the river. (答案：A)A. playingB. to be playingC. playD. to play(5)动词不定式（短语）作定语：动词不定式（短语）作定语需后置。
*动词不定式作定语与分词作定语的区别:过去分词表示动作已经完成，现在分词表示动作正在发生当中，而不定式则表示将要发生的动作或状态。
辨析: The meeting held is important. (表示动作已经完成)The meeting being held is important. (表示动作正在进行当中)The meeting to be held is important. (表示动作将要发生)注意：1)当被修饰的是不定代词如everything, anything, much, little等,或被修饰的名词前被形容词最高级,序数词,the only等强调结构修饰时,非谓语动词作定语则用动词不定式。
Do you have anything to say? 你有什么要说的吗?I am afraid I cannot attend your party, for I have too many things to do.He is the only person to know the truth. 他是唯一了解真相的人。
When the question was out, he was the first one to raise his hand….他第一个举起手。
He was the last to realize the importance of this problem.2)如被修饰的名词或代词是动词不定式的逻辑宾语，且动词不定式的动词是不及物动词,则后面需跟成为搭配的介词。
Who is the man to talk to? 要谈话的人是谁？He is a tough teacher to deal with. 他是个很难对付的老师。
I need a pen to write with. 我需要一支笔写字例如:To fetch water before breakfast seemed to me a rule_____.（上海高考题98）：A. to never breakB. never to be brokenC. never to have brokenD. never to be breaking 答案是B，在句中作定语；由于a rule是不定式的逻辑宾语，所以不定式用了被动结构。
又如：There are five pairs____, but I’m at a loss which to buy.（上海高考题99）A. to be chosenB. to choose fromC. to chooseD. for choosing答案是B，这是“不定式 + 介词”作定语。
