英语语法精讲：不定式

常用于及物动词: want , hope, wish, like, need, hate, offer, prefer, begin, start, attempt, decide, determine, expect, promise, pretend, refuse ,afford, manage, help等之后，如：

You should continue to learn as long as you live.

注1：如果作宾语的不定式又有自己的补语，则须用先行词it 作形式宾语，而将真正的宾语不定式后置，如：

They found it impossible to get everything ready in time.

注2：不定式一般不能作介词的宾语，只有在极少数介词如:but, except等后边才行。此时不定式可以带to或不带to,如：

In very cold winter weather a cold-blooded animal has no choice but to lie down and sleep.

There was nothing left to do but clean the windows.(前边有do, to 省略) 但“疑问词+不定式”结构可以作介词的宾语，如：

I have no idea about what to do next.

(4)作宾语补足语

通常用于及物动词或动词短语：want ,wish, ask, order, beg, tell, permit, know, help, advise, persuade, allow, prepare, cause, force, require, call on, wait for等之后，如：

The teacher asked the students to hand in their homework.

(5)作定语

不定式作定语时，须放在被它修饰的名词或代词之后。被修饰的名词或代词往往是不定式的逻辑宾语

I have a lot of work to do.

当作定语的不定式所修饰的名词或代词是不定式动作的承受者时，不定式既可用主动语态，又可用被动语态，但其含义有所不同。所以如果修饰名词的不定式的动作是主语作的, 不定式用主动