一般時 to do to be done
進行時 to be doing
完成時 to have done to have been done
完成進行時 to have been doing
To speak good English is not easy.
or: It is not easy to speak good English.
(采用形式主語 it 以避免頭重腳輕)
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.
Hewants his son to study hard.
不定式作賓補，如謂語動詞是感官動詞，使役性動詞(see, hear, notice, watch, make, have, let...)，則不定式符號“to”須省略，但在被動語態中不能省。
I heard them sing in the classroom.
I made her clean the room.
The girl is heard to sing an English song.
(4)用作表語：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.(結果)
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.(現在情況)
She seems to be dancing in the dancing hall.(正在進行)
She seems to have danced well.(過去情況)
Has was happy to have been staying with his uncle.(動作持續一段時間)
The doctor recommended 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.