一般时 to do to be done
进行时 to be doing
完成时 to have done to have been done
完成进行时 to have been doing
To speak good English is not easy.
or: It is not easy to speak good English.
（采用形式主语 it 以避免头重脚轻）
It took me an hour to do the work.
She decided to take the examination.
I hope to meet him soon.
They expected us to help them.
He wants his son to study hard.
不定式作宾补，如谓语动词是感官动词，使役性动词（see, hear, notice, watch, make, have, let...），则不定式符号“to”须省略，但在被动语态中不能省。
I heard them sing in the classroom.
I made her clean the room.
The girl is heard to sing an English song.
To teach is to learn.
His job is to sell cars.
We come to school to study English.（目的）
= in order to
I hurried to the store, only to find it closed.（结果）
He asked for a piece of paper to write it on.
= to write it on the piece of paper.
The poor man has no house to live in.
= to live in the house.
Have you anything to do?
= to do anything
She seems to dance very well.（现在情况）
She seems to be dancing in the dancing hall.（正在进行）
She seems to have danced well.（过去情况）
Has was happy to have been staying with his uncle.（动作持续一段时间）
The doctor [wrecommend]recommended[/w] him to air the room.
The doctor recommended the room to be aired.
She expects the police to find her bicycle.
She expects her bicycle to be found by the police.
She felt a bit puzzled as he had asked her such a question.
She felt a bit puzzled to have been asked such a question.
6．不定式否定形式：not to do ...
He got up early in order not to miss the train.
1. Did you find out ________ the pie out of oven?
A. to take B. have taken C. when to take D. being taken
2. You would be irritated if you watched the mail ________ on your desk every day.
A. putting up B. to be put up C. to pile up D. pile up
3. We shall set Jim ________ the passage.
A. explaining B. explained C. to explain D. explain
4. In fact, she would rather leave for San Francisco ________ in Los Angeles.
A. tostay B. than stay C. than staying D. than have stayed
5. Madame Curies is believed ________ the radium.
A. discovering B. having discovered C. to have discovered D. to discover
1. C 2. D 3. C 4. B 5. C