定义：动词不定式是非谓语动词的一种，它没有人称和数的变化，在句子中不能独立作谓语，但它仍保持动词的特点，既可以有自己的宾语和状语。 E.g. He want his students to read the book aloud.
A.
1不定式的构成 (以动词do为例)
主动形式 被动形式
一般式 to do to be done
完成式 to have done to have been done
进行式 to be doing 无
完成进行式 to have been doing 无
2?不定式的意义
不定式的一般式(to do )
一般式表示的动作或状态，发生在谓语动词表示的动作或状态的同时或之后
My wish is to become a doctor
He seemed to be tired.
She stopped to have a rest.
不定式的被动式 (to be done)
当不定式的逻辑主语是这个不定式所表示的动作的承受者时,不定式一般要用被动式.
The building to be finished next month is for our teachers.
I am going to Beijing, I have something to take to my parents, do you have something to be taken to your parents?
如果谓语表示的动作(情况)发生时, 不定式表示动作正在进行,这时候不定式就要用进行式.(to be doing)
They are said to be building another bridge across the street.
They seemed to be talking about something important.
When I went to his home, he happened to be traveling around the world.
I’m glad to be working with you.
如果不定式所表示的动作或状态发生在谓语动词所表示动作或状态之前，就用完成式 (to have done) ;若是在此基础上的被动含义，就用完成被动式( to have been done).
He is said to have written a novel about the Long March.
He thought it a pity not to have invited us.
The assistant seemed to have been fired.
He is said to have been taught French when he was a child.
Einstein is said to have built up his theory when he was in his twenties.
如果不定式的动作是在谓语所表示的时间之前一直在进行的动作，就要用完成进行式.
They are said to have been collecting folk song in Xinjiang.
We’re happy to have been working with the experts all the month.
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