动词不定式的用法.doc

动词不定式的用法
概念:
动词不定式由to+动词原形构成。这里的to是不定式标志,没有词义。不定式具有名词、形容词或副词的某些语法功能,又有动词的时态和语态的特点及作用。可以做主语、宾语、宾语补足语、表语、定语、状语。
一、作主语
动词不定式作主语时,句子的谓语动词常用单数,其位置有以下两种:
(1)把不定式置于句首。如:
To get there by bike will take us half an hour.
(2)用it作形式主语,把真正的主语不定式置于句后,常用于下列句式中。如:
①It+be+名词+to do
It's our duty to take good care of the old.
②It takes sb+some time+to do
How long did it take you to finish the work?
③It+be+形容词+b+to do
It is difficult for us to finish for swriting position in a quarter of an hour.
在句型③中,常用表示客观情况的形容词,如:
easy, difficult, hard, important, possible, impossible, comfortable, necessary, better;
the first, the next, the last, the best, too much, too little, not enough
④It+be+形容词+of sb+to do
It is stupid of you to write down everything the teacher says.
在句型④中,常用careless,clever,good,foolish,honest,kind,lazy,nice,right,silly,stupid,wise rude, clever, foolish, thoughtful, thoughtless
(欠考虑的;不考虑的), brave, considerate(考虑周到的), selfish(自私的)等表示赞扬或批评的词。在不定式前的sb,可看作其逻辑主语。这一句式有时相当于Sb is+形容词+to do句式,如:It's kind of you to help me with my English.=You are kind to help me with my English.
⑤It seems(appears)+形容词+to do
It seemed impossible to save money.
It seemed selfish of him not to give them anything. 他不给他们任何东西,这显得太自私了。
注意:1) 其他系动词如,look,appear等也可用于此句型
2) 不定式作为句子主语时,动词用单数形式。
3) 当不定式作主语的句子中又有一个不定式作表语时,不能用It is… to…的句型
对应性:To see is to believe. 百闻不如一见。
二、作宾语
1) 以下动词后,只能跟不定式作宾语
afford (付得起),agree(同意),aim(力求做到), appear(显得),arrange(安排),ask(要求),attempt (试图),care(想要),choose(决定),claim(声称),condescend(屈尊),consent(准许),decide(决定),demand(要求),determine(决心),endeavor(竭力),expect(期待),fail(未履行),help(帮助),hesitate(犹豫),hope(希望),learn(学会),manage(设法),neglect(疏忽),offer(主动提出),plan(计划),prepare(准备),pretend(假装),proceed(接着做),promise(答应),prove(证明),refuse(拒绝),resolve(解决),seem(觉得好像),swear(发誓),tend(往往会),threaten(
威胁),undertake(承诺),volunteer(自愿做),vow(发誓),want(想要),wish(希望)
举例:
The driver failed to see the other car in time.
司机没能及时看见另一辆车。
I happen to