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. expected
B. to expect
C. to be expecting
D. 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 have
B. having
C. have
D. 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 with
B. what to do it with
C. what to do with it
D. 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 off
B. turn it off
C. to turn it off
D. 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. learn
B. to learn
C. learned
D. 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. playing
B. to be playing
C. play
D. 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)
