4.不定式作定语

不定式作定语相当于一个定语从句，它修饰以下几类名词：
⑴由动词派生或转化而来的名词，它们所对应的动词通常有不定式作宾语。
Another attempt to climb the mountain will be made next month. in his speech he expressed his determination to achieve the goal. 这类名词主要有：attempt， claim， decision， plan， promise， intention， need， resolution，tendency， wish， failure， threat等。
⑵由可能与不定式搭配的形容词派生出来的名词。
Her eagerness to learn a foreign language obvious.这类名词主要有：anxiety， patience， ability， willingness， ambition等。
⑶不定式作定语还可用来修饰代词something， anything， everything，  nothing. 
she has everything to lose and nothing to gain.
⑷由only， last，  next， 序数词或形容词最高级修饰的名词后常用不定式作定语。
Jim is the only student to answer the question correctly in his class. you are the last to undertake the blood test.
⑸ 不定式常作为定语修饰there be结构的真实主语。
There is a big task to complete.
⑹ 有些抽象名词。主要有：reason， right， time， effort， chance， way等。如：  the time to go to school， the way to get to the clinic，  the chance to win the game.

5.不定式作状语

不定式作状语相当于一个状语从句，表示形为的目的、结果或原因。
⑴表示目的。在这种情况下，不定式的逻辑主语通常也是全句的主语。
He stayed there to see what would happen.在强调不定式目的状语时，不定式前可加in order， so as等。如：
She asked me to drive her to the airport in order to catch the 5： 00 plane. he moved the tv set to the meeting-room so as to let everyone watch it.
⑵用so……as to……， such （……） as to……， enough to……， too……to， only to等表示结果，如：
Have you got enough room to seat all of us？
She is too weak to join us in the outing.
⑶将不定式移到句首表示条件，如：
to hear the teacher better， you have to sit in the front. = if you are to hear the teacher better，……
⑷与形容词连用时，大多表示原因。这些形容词主要有：happy， kind， surprised， frightened， angry， shocked， glad， delighted， grieved，disappointed等。
They were surprised to be informed of the news. i‘m glad to hear this.

动词不定式的时态和语态

一般式 to do to be done
完成式 to have done to have been done
进行式 to be doing
完成进行式 to have been doing

1.如果不定式所表示的动作与主要谓语动词所表示的动作同时（或几乎同时）发生或发生在主要谓语之后，通常用不定式的一般形式。如：
I saw him go out.
I‘m glad to see you.

2.如果不定式所表示的动作发生在主要谓语动词或特定的时间之前，不定式就要用完成式。如：
I intended to have telephoned you， but i forgot to.
I should like to have bought a dictionary.

3.不定式进行式表示主要谓语动词所表示的动作发生时，不定式所表示的动作正在发生。如：
I am glad to be talking with you. she pretended to be listening attentively. 

4.不定式完成进行时表示的是一个开始于过去某一时刻但一直延续到谓语动词发生的那一时刻的动作。如：
He was thought to have been working on the project for two years.

5.不定式的被动语态
当不定式的逻辑主语是动作的承受者时，这个不定式要用被动式，包括它的各种时态在内。如：
She doesn‘t like to be treated as a guest.
她不喜欢被当作客人对待。
They want their tv set to be fixed right now.