时间:2018-10-18 英语知识 我要投稿
  1.作主语。 如:  To learn English is very important.  但实际上不定式作主语常用 it来作形式主语,而将不定式移至谓语动词后作真正的主语。  如上句可表达为:  It's very important to learn English.  2.作表语。 如:  My idea is to ring him up at once.  3.作宾语。 如:  I have decided to go to Binjiang Primary School.  4.作宾语补足语。  a. ask, want, teach, tell, know, would like, allow等动词后面接动词不定式作宾语补足语。  如: The policemen asked him to get off the bus.  b. hear, see, look at, feel, watch, notice, listen to等动词后接不带to的动词不定式作宾语补足语。  如: We often see Miss Li clean the classroom.  c. let, make, have这些使役动词后接不带to的动词不定式作宾语补足语。但在被动语态中这些不带to的都须带上to。  如: In those days the bosses often made the workers work day and night.  d.动词help接动词不定式作宾语补足语,可带to也可不带to。  如: Can you help me (to) carry the heavy bag?  5.作定语。  a.与被修饰词有动宾关系。如:I have something important to tell you.但如果不定式动词为不及物动词,后面的介词千万不要省略。  如: Maybe they have three rooms to live in.  b.与被修饰词有主谓关系。  如: Mr Liang is always the first to come and the last to leave.  c.与被修饰之间只有修饰关系。  如: I have no time to play cards.  6.作状语,表示目的、原因、方法、方向、结果等。  如: I'll go to meet my friend at the railway station.  7.不定式复合结构"for sb. to do sth" 作主语时,常用"It is +adj+ for  of sb. to do sth"的句式。形容词good, bad, polite, unkind, kind, ice, clever,  right, wrong, careful等用"It is +adj +of sb. to do sth."  其他形容词用 for。  如:  It's dangerous for you to ride so fast.  It's very kind of you to help me.  8.动词不定式与疑问句who, what, which, when, how, where, whether等连用。  如: I don't know when to start.  He didn't tell me where to go.  但上面结构相当于一个从句,故上述句子也可表达为:  I don't know when we'll start.  He didn't tell me where he would go.  注意:  a.有些动词或动词短语不能带不定式,只能接动词的-ing形式。  如: enjoy, finish, keep, mind, miss(错过),be busy, go on, keep on, be worth, practise等。  如: The peasants are busy picking apples.  Would you mind my opening the door?  b.有些动词后可接不定式,也可接动词的-ing形式,但意思不同。  如: Lu Jian forgot to post the letter.(该寄但还没做)  Lu Jian forgot posting the letter.(已经寄过信了)  They stopped to sing a song.(停止在做的工作而去做另一件工作)  They stopped singing.(停止正在做的工作)