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。
