動詞不定式有主動語態和被動語態，在句子中作主語，表語和賓語等
動詞不定式有主動語態和被動語態。
一 動詞不定式的主動語態有5種形式
一般式 to do (to do sth是動詞不定式短語）
進行式to be doing
完成式 to have done(done代表過去分詞 ）
完成進行式to be doing
動詞不定式的被動語態有2種形式
一般式 to be done
完成式 to have been done
否定式 not +to do
動詞不定式用法
二 動詞不定式用法：在句子中充當主語，賓語，定語，賓語補足語等句子成分，及其他用法。
1動詞不定式（短語）作主語
To rebuild the factory will take them 3 years.
他們要重修這個工廠得3年。
常用it作形式主語，動詞不定式（短語）作真實主語。
It is difficult to imagine the modern world without oil.
很難想象沒有油的現代世界。
疑問詞+動詞不定式（短語）作主語
When to start remains undecided.出發時間還未定。
其他句式：It seems/appears adj to do sth
It seems impossible to save money.攢錢是不可能的。
It be動詞 adj for/of sb to do sth
It was silly of us to believe him.我們真傻居然相信他們。
It be動詞 + sb some time to do sth
It
’
s our duty to take care of the old.
照顧老人是我們的責任。
2 動詞不定式作表語
His dream is to be a businessman.
他的夢想是成為一名商人。
The question is how to get there.
問題是怎樣到達那裡。（疑問詞+動詞不定式）
注意：有時可以省略to
The only thing I can do now is (to) go on by myself.
我現在唯一能做的就是自己繼續進行下去。
What I want to say is (to) be yourself .
我想說的就是做你自己。
3 動詞不定式作賓語
及物動詞（vt) +動詞不定式,這類動詞有:afford, want, wish, learn, like ,forget, hope, intend, determine,expect, fail, begin, attempt， care to do sth願意/喜歡做某事, claim聲稱, continue,choose, agree, decline, desire, determine, try,undertake, manage設法， mean, refuse, promise, remember, require, offer主動提出，seek, start，ask, arrange安排，pretend假裝，beg懇求等。
有時可用it作形式賓語，動詞不定式作真正賓語。這些動詞常有：believe,consider,think, feel, find, imagine, know, make, prove, realize,show, suppose, think, understand等。
We think it very important for us to learn a foreign language well.
我想對我們來說學好一門外語是很重要的。
疑問詞+動詞不定式也可作賓語
I don
’
t decide where to live.我沒有決定住哪裡。
where作副詞，所以live後面不加介詞in.
I don
’
t decide which room to live in.
我沒有決定住哪個房間。
I don
’
t know what to do. 我不知道做什麼。
I don
’
t know how to do it. 我不知道怎麼做。
4 動詞不定式作定語
His book to be published next month is based on a true story.
他下個月將被出版的書是以真實的故事為基礎的。
to be published next month作定語，修飾book
My wish to visit France has come true at last.
我想去法國旅遊的願望終於實現了。
I borrowed some books to read during the holiday.
我借了一些假期要讀的書。to read這個動作發生在借之後。
They have a big house to live in.他們有大房子住。
介詞in不能省略。
當前面名詞是time，place或way時，不定式後面的介詞習慣省去。
He had no place to go.他沒有地方去。
They had no place to live.他們沒有地方住。
Mice ran out of the fields looking for places to hide.
老鼠從地裡跑出去找地方躲藏。
注意：I have something to send.= I have something to be sent.
我有些東西要寄。
5動詞不定式作狀語
目的狀語 He ran so fast as to catch the first bus.
他跑得這麼快為了趕上頭班車。
結果狀語 He searched the room only to find nothing.
他找遍了這個房間結果卻一無所獲。
原因狀語 I
’
m glad to see you. 見到你我很高興。
I
’
m very happy to have passed the exam.
我很高興已經通過了考試。
評註性狀語To be honest, I don
’
t like western food.
6 動詞不定式作補語
在ask, want, encourage, wish, advise,forbid, allow, expect, find, get, invite, tell,remind, consider等動詞後可以跟動詞不定式作賓語補足語。
We saw them enter the house. 我看到他們進入房間。賓語補足語
They were seen to enter the house. 他們被看到進入房間。to enter the house 作主語補足語。
My father doesn
’
t allow us to play on the street.
我爸爸不讓我們在街上玩。
在感官動詞後，如feel, see,hear, watch, look at, listen,notice, observe,在使役動詞，如let, make, have後，不定式省略to.
He noticed someone leave the room.他注意到了有人離開房間。
變成被動後，要加上to. They were made to retell the text by the teacher.老師要他們複述課文。
People found that they have moved out.
=They were found to have moved out.他們被發現已經搬走了。
to have moved out作主語補足語。
It is said that they have developed a new technique.
= They are said to have developed a new technique.
據說人們已經發研發了一項新技術。
to have developed a new technique作主語補足語。
7 動詞不定式構成片語
be free to do something 有空做某事
be afraid to do something 害怕作某事
be careful to do something 認真做某事
too...to 太... 而不能...
The hat is too large to wear. 這帽子太大，沒法戴。
8 動詞不定式主動形式表被動意義
The book is difficult to understand. 這本書很難理解。
We must know what to say at the meeting.
我們必須知道會上說什麼。
It is impossible to finish. 不可能完成。
The house is to let.此房出租。
She was to blame for the accident.
她應該為這次交通事故負責。
