非谓语动词

　　一、动词不定式

　　一)、不定式结构作主语

　　To see one time is better than to hear a hundred times.

　　To persevere means victory!

　　注①：在很多情况下，特别是在口语中，常采用先行it代替主语，而把不定式后置：

　　It’s a great pleasure to be here.

　　It is not an easy thing to master a language.

　　注②：这种后置不定式的结构也适用于某些谓语动词不是系动词的句子，如：

　　It took us five hours to get there.

　　It made us very angry to hear him talk like that.

　　注③：不定式结构的逻辑主语通常可在特定的上下文或情景中看出，也可以由“ for + 名词词组” 来表示，如：

　　It is not hard for one to do a bit of good.

　　It was difficult for me to do the work.

　　注④：某些形容词在上述结构中作表语时，常在不定式之前加上 “of + 名词词组” 来说明不定式所指的是谁的情况，如：

　　It’s kind of you to think so much of us.

　　It’s very nice of you to be so considerate.

　　It’s unwise of them to turn down the proposal.

　　It was careless of her to make such a mistake.

　　二)、不定式结构作表语

　　1.主语和表语都是不定式(其含义往往一是条件，一是结果)，如：

　　To be kind to the enemy is to be cruel to the people.

　　To do that would be to cut the foot to fit the shoe.

　　2.主语是以aim, duty, hope, idea, intention, mistake, plan, proposal, job, suggestion 等为中心词的名词词组，或以 what 引导的名词性从句表示，后面的不定式说明其内容，如：

　　My idea is to climb the mountain from the north.

　　Your mistake was not to write that letter.

　　My suggestion is to start work at once.

　　What I would suggest is to start work at once.

　　注：在某些句型中，当主语部分有动作动词do 时，作表语的不定式可以省略符号 “to”，如：

　　All we have to do is push the button.

　　The only thing I can do now is go on by myself.

　　All I could do was send him a telegram.