动词不定式（The Infinitive）二、不定式的主要用法动词不等式具有名词、形容词及副词的特征，因此在句中可作主语、宾语、宾语（或主语）补足语、表语、定语、及状语等。

1、不定式作主语①不等式作主语时，谓语动词用单数形式。

To conquer English is not easy. 征服英语不容易。

To make plan firs t is a good idea. 先制定计划是个好主意。

To know everything is to know nothing. 事事皆通，无一精通。

②不等式作主语时，常常用形式主语it替代，而将真正的主语不等式放在句子的后面。

It is necessary to master a foreign language.掌握一门外语很有必要。

It’s a great pleasure to see you again.再次见到你真高兴。

It is a bad manner to stare at a foreign guest.盯着外宾看是一种不良的举动。

③如果说明不等式表示的动作是谁做的，可以在不等式的前面加一个for引起的短语，这就是常见的“It is adj./n. for sb. to do sth.”句式。

如：It is good manners for an Arab to stand close to his friends when they are talking.对阿拉伯人来说，交谈时站得离朋友近些是好的礼貌。

It is a great honor for us to be presented at the party.我们能来参加晚会，深感荣幸。

It will be a regret for us not to help him. 我们没有帮助他是个遗憾。

④在某些形容词（如kind, good, nice, wise, unwise, clever, silly, wrong, right, foolish, stupid, careless, considerate, rude, naughty, impolite等）作表语时，不等式前常加一个以of引起的短语，来说明不等式指的是谁的情况。

这就是常见的“It is adj. of sb to do sth.”句式。

如：It’s very kind of you to think so much of us. 谢谢你替我们考虑这么多。

It is unwise of them to do like that. 他们那样做是不明智的。

It’s impolite of you to gossip about others.你们说别人的闲话是不礼貌的。

It’s careless of them to ignore this important point.他们忽视了重点，只是粗心。

2、不定式作宾语①英语中能以不等式作宾语的动词很多。

常见的有：like, want, wish, hate, prefer, hope, manage, try, offer, start, ask, forget, promise, pretend, intend, begin, attempt, decide, desire, agree, learn, choose, expect等等。

如：Don’t forget to bring your dictionary.不要忘记把你的字典带来。

He can’t afford to buy a car.他买不起小汽车。

I need to fetch a tape from a friend. 我需要去一个朋友处取一盒磁带回来。

We’ve decided to put on a short play next week. 我们决定下一周演一个小话剧。

Once you start to smoke, you cannot easily give it up. 一旦你抽上了烟，你就不容易戒掉。

I really like to watch football matches. 我非常喜欢看足球比赛。

How I wish to see my old friends again. 我多么想再见到我的老朋友啊！②当不等式作直接宾语，而后面还有宾语补足语时，通常把不等式放在补足语后面，而用形式宾语it来替代它。

如：I found it impossible to answer all the questions within the time given.我发现在限定的时间内回答所有的问题是不可能的。

She thought it unnecessary to argue with him about it.她觉得没有必要和他辩论这问题。

He made it a rule only to speak English in class. 他规定课上只能说英语。

I find it necessary to speak about our shortcomings. 我觉得有必要谈谈我们的缺点。

She feels it hardly to help others. 她认为帮助别人是她的责任。

③英语中介词后面通常要用动词的动名词形式。

但是下面的这些短语中的介词却例外：be about to +不等式，do nothing but, cannot help choose but, nothing except, nothing else than，cannot but 等。

如：He is about to go aboard to study. 他将出国学习去了。

The patient can not but follow the doctor’s instructions, though he doesn’t think it necessary.病人只得遵照医生的嘱咐，尽管他们认为没有必要。

These children did nothing except play all day long. 这些孩子除了整天玩外，什么都没做。

He did nothing else than laugh. 他只是笑。

He does everything except go to school. 他怎么也不上学。

I had no choice but to give up this chance to go aboard. 我没有办法只好放弃了此次出国的机会。

I have got nothing to do but depend on myself. 我没有办法只好依靠自己。

★ [注意] but、except用作介词（除……之外）接不等式，如前面有do/does/did时，不等式不带to，否则要带to。

再如：The lady can do nothing but give in. = The lady has no choice but to give in.3、不定式作宾语补足语在很多句子中，不定式用作宾语（名词或代词）的补足语，从而构成复合结构，即复合宾语。

句子的宾语与不定式之间在逻辑上是主谓关系。

这坟种情况：①带to的不等式作宾语补足语。

要求带这种结构的常见动词有：ask 要求 want 想要 order 命令 tell 告诉 like 喜欢 get 使allow 允许know 知道help 帮助persuade 说服advise 建议permit 允许teach 教beg 祈求warn 警告encourage 鼓励forbid 禁止cause 导致invite 邀请force 逼迫require 要求wish 希望warn 警告request 要求forbid 禁止invite 邀请cause 导致advise 劝告urge 敦促；促使The teacher asked us to recite the texts. 老师要我们背诵课文。

We didn’t want this to happen. 我们并不希望发生这样的事。

I told Jeff to join the club, but he wouldn’t listen. 我告诉Jeff让他加入俱乐部，但他不听。

I expected her to arrive on Sunday. 我希望她星期天到。

They encouraged me to try again. 他们鼓励我再试一次。

I’ll get someone to repair your bike. 我去找个人来帮你修自行车。

②不带to的不等式作宾语补足语。

要求带这种结构的常见动词有（但这些动词的被动形式需要带to）：see 看见notice 注意watch 仔细看look at 看见discover 发现observe 观察hear 听见listen to 听feel 感觉make 使let 让have 让Nothing will make me change my mind. 什么也改变不了我的注意。

Nobody saw him come in.谁也没看见他进来。

We listened to the band play in the park.我们在公园听乐队演奏。

She was seen to enter the room about the time he was leaving. 他走的时候看到她进入房间。

★特别注意：上述这些动词的被动语态一定要加上to.另外，主动语态动词help后的复合宾语中的不等式可带to，亦可不带to.而被动语态必须加toShe often helps her parents (to) wash clothes. 她经常帮爸妈洗衣服。

= Her parents are often helped to wash clothes.I won’t be made to change my mind by anything.He wasn’t seen to come in by anyone.The band was listened to play in the bank.③有些成语动词后面的复合宾语中用带to的不等式；常见的有：wait for, call on, count on/upon, vote for, rely on, depend on/upon, long for, care for, prevail upon等。

但是在listen to, look at后面的复合宾语的不等式则不带to.I’m counting on him to help me through. 我指望他能我度过难关。