否定式：not + (to) do
(1) 一般式：不定式的一般式所表示的动作与谓语动词动作同时发生或发生在谓语动词动作之后, 例如：I'm glad to meet you.
(2)进行式：不定式的进行式所表示的动作与谓语动词动作同时发生,例如：The boy pretended to be working hard.
(3)完成式：不定式的完成式表示的动作发生在谓语动词动作之前,例如：I regretted to have told a lie.
To finish the work in ten minutes is very hard.
It is very hard to finish the work in ten minutes.
Her job is to clean the hall.
常与不定式做宾语连用的动词有：want, hope, wish, offer, fail, plan, learn, pretend, refuse, manage, help, agree, promise, prefer, 如果不定式(宾语)后面有宾语补足语,则用it作形式宾语,真正的宾语(不定式)后置,放在宾语补足语后面,例如：
Marx found it important to study the situation in Russia.
在复合宾语中,动词不定式可充当宾语补足语,如下动词常跟这种复合宾语：want, wish, ask, tell, order, beg, permit, help, advise, persuade, allow, prepare, cause, force, call on, wait for, invite.
I have a meeting to attend.
He found a good house to live in.
The child has nothing to worry about.
What did you open it with?
如果不定式修饰time, place, way,可以省略介词：
He has no place to live.
This is the best way to work out this problem.
Have you got anything to send?
Have you got anything to be sent?
We have made a plan to finish the work.
He is the first to get here.
He worked day and night to get the money.
She sold her hair to buy the watch chain.
wrong：To save money, every means has been tried.
right：To save money, he has tried every means.
wrong：To learn English well, a dictionary is needed.
right：To learn English well, he needs a dictionary.
He arrived late to find the train gone.
I visited him only to find him out.
They were very sad to hear the news.
It's too dark for us to see anything.
The question is simple for him to answer.