不定式的特殊句型too…to…
1) too…to　 太…以至于…
He is too excited to speak. 他太激动了，说不出话来。
---- Can I help you ? 需要我帮忙吗?
---- Well, I'm afraid the box is too heavy for you to carry it, but thank you all the same.　不用了。这箱子太重，恐怕你搬不动。谢谢您。
2) 如在too前有否定词，则整个句子用否定词表达肯定， too 后那个词表达一种委婉含义，意 为"不太"。
It's never too late to mend.　(谚语)　改过不嫌晚。
3) 当too 前面有only, all, but时，意思是：非常… 等于very。
I'm only too pleased to be able to help you. 我非常高兴能帮助你。
He was but too eager to get home. 他非常想回家。

不定式的特殊句型so as to
1) 表示目的；它的否定式是so as not to do。
Tom kept quiet about the accident so as not to lose his job.　汤姆对事故保持沉默是为了不丢掉他的工作。
Go in quietly so as not to wake the baby.  轻点进去，别惊醒了婴儿。
2) so kind as to ---劳驾
Would you be so kind as to tell me the time? 劳驾，现在几点了。

不定式的特殊句型Why not
"Why not +动词原形"表达向某人提出建议，翻译为："为什么不……?" "干吗不……?"
例如：Why not take a holiday?　干吗不去度假?

不定式的时态和语态

 时态\语态  主动  被动
 一般式  to do  to be done
 进行式  to be doing  
 完成式  to have done  to have been done
 完成进行式  to have been doing  

1) 现在时：一般现在时表示的动词，有时与谓语动词表示的动作同时发生，有时发生在谓语动词的动作之后。
He seems to know this.
I hope to see you again. = I hope that I'll see you again.　我希望再见到你。
2) 完成时：表示的动作发生在谓语动词表示的动作之前。
I'm sorry to have given you so much trouble.
He seems to have caught a cold.
3) 进行时： 表示动作正在进行，与谓语动词表示的动作同时发生。
He seems to be eating something.
4) 完成进行时：
She is known¹ to have been wreaking² on the problem for many years.

动名词与不定式
1) 动名词与不定式的区别：
动名词表达的是： 状态，性质，心境，抽象，经常性，已发生的
不定式表达的是： 目的，结果，原因，具体，一次性，将发生的
2) 接不定式或动名词，意义相同。
3) 动名词与不定式语义不同的有11 组：

 stop to do  stop doing
 forget to do  forget doing
 remember to do  remember doing
 cease³ to do  cease doing
 try to do  try doing
 go on to do  go on doing 
 afraid to do   afraid doing
 interested to do  interested doing 
 mean to do  mean doing 
 regret to do  regret doing
 begin/start to do  begin/start doing 

特殊词精讲
stop doing/to do
stop to do　停止，中断做某事后去做另一件事。
stop doing　停止做某事。
They stop to smoke a cigarette.　他们停下来，抽了根烟。
I must stop smoking⁴. 我必须戒烟了。

典型例题
She reached the top of the hill and stopped ___　on a big rock by the side of the path.　
A. to have rested　B. resting　 C. to rest　D. rest
答案：C。由题意可知，她到了山顶，停下来在一个路边的大石头上休息。因此，应选择"stop to do sth. 停下来去做另一件事"。而不仅仅是爬山动作的终止，所以stop doing sth.不正确。

stop doing/to do

forget doing/to do
forget to do　忘记要去做某事。　(未做)
forget doing　忘记做过某事。　　(已做)
The light in the office is stil on. He forgot to turn it off. 办公室的灯还在亮着，它忘记关了。(没有做关灯的动作)
He forgot turning the light off. 他忘记他已经关了灯了。( 已做过关灯的动作)
Don't forget to come tomorrow. 别忘了明天来。(to come动作未做)

典型例题
---- The light in the office is still on.
---- Oh, I forgot___.　　　　　　　　　　
A. turning it off　 B. turn it off　 C. to turn it off　 D. having turned it off
答案：C。由the light is still on 可知灯亮着，即关灯的动作没有发生，因此用forget to do sth.
而forget doing sth表示灯已经关上了，而自己忘记了这一事实。此处不符合题意。

remember doing/to do
remember to do 记得去做某事　　　　 (未做)
remember doing　记得做过某事　　　 (已做)
Remember to go to the post office after school. 记着放学后去趟邮局。
Don't you remember seeing the man before? 你不记得以前见过那个人吗?

regret doing/to do
regret to do　 对要做的事遗憾。　(未做)
regret doing　 对做过的事遗憾、后悔。　(已做)
I regret to have to do this, but I have no choice. 我很遗憾必须这样去做，我实在没有办法。
I don't regret telling her what I thought.　我不为告诉她我的想法而后悔。

典型例题
---You were brave enough to raise objections⁵ at the meeting.
---Well, now I regret ___ that.
A. to do　 B. to be doing　 C.　to have done　 D.　having done
答案：D。regret having done sth. 对已发生的事感到遗憾。regret to do sth. 对将要做的事感到遗憾。本题为对已说的话感到后悔，因此选D。

cease doing/to do
cease to do　 长时间，甚至永远停做某事。
cease doing　 短时停止做某事，以后还会接着做。
That department has ceased⁶ to exist forever. 那个部门已不复存在。
The girls ceased chatting for a moment when their teacher passed by.　姑娘们在老师走过时，停了会聊天。

try doing/to do
try to do　　努力，企图做某事。
try doing　 试验，试着做某事。
You must try to be more careful.　你可要多加小心。
I tried gardening⁷ but didn't succeed. 我试着种果木花卉，但未成功。

go on doing/to do
go on to do　做了一件事后，接着做另一件事。
go on doing　 继续做原来做的事。
After he had finished his maths，he went on to do his physics. 做完数学后，他接着去做物理。
Go on doing the other exercise after you have finished this one. 作完这个练习后，接着做其他的练习

be afraid doing/to do
be afraid to do　不敢，胆怯去做某事，是主观上的原因不去做，意为"怕"；
be afraid of doing　担心出现doing的状况、结果。 doing 是客观上造成的，意为"生怕，恐怕"。
She was afraid to step further in grass because she was afraid of being bitten by a snake. 她生怕被蛇咬着，而不敢在草丛中再走一步。
She was afraid to wake her husband. 她不敢去叫醒她丈夫。
She was afraid of waking her husband. 她生怕吵醒她丈夫。

be interested doing/to do
interested to do　　 对做某事感兴趣，想了解某事。
interested in doing　 对某种想法感兴趣，doing 通常为想法。
I shall be interested to know what happens. 我很想知道发生了什么事。 (想了解)
I'm interested in working in Switzerland. Do you have any idea about that? 我对在瑞士工作感兴趣。你想过这事吗?　 (一种想法)

mean to doing/to do
mean to do　 打算、想
mean doing　意味着
I mean to go, but my father would not allow me to. 我想去，但是我父亲不肯让我去。
To raise wage means⁸ increasing purchasing power. 赠加工资意味着增加购买力。

begin(start) doing/to do
begin / start to do sth
begin / start doing sth.
1) 谈及一项长期活动或开始一种习惯时，使用doing.
How old were you when you first started playing the piano? 你几岁时开始弹钢琴？
2) begin, start用进行时时，后面动词用不定式to do
I was beginning to get angry.　我开始生起气来。
3) 在attempt, intend, begin, start 后接know, understand, realize这类动词时，常用不定式to do。
I begin to understand the truth.　我开始明白真相。
4) 物作主语时
It began to melt⁹.
感官动词 + doing/to do
感官动词 see, watch, observe, notice, look at, hear, listen to, smell, taste, feel + do　 表示动作的完整性，真实性；+doing 表示动作的连续性，进行性
I saw him work in the garden yesterday.　昨天我看见他在花园里干活了。(强调"我看见了"这个事实)
I saw him working in the garden yesterday. (强调"我见他正干活"这个动作)昨天我见他正在花园里干活。

典型例题
1) They knew her very well. They had seen her ___ up from childhood.　
A. grow　 B. grew　 C. was growing　 D. to grow
答案：A. 因题意为，他们看着她长大，因此强调的是成长的过程，而非正在长的动作，因此用see sb do sth 的句型。

2) The missing¹⁰ boy was last seen ___ near the river.　
A. playing　 B. to be playing　　C. play　　D. to play
答案：A. 本题强调其动作，正在河边玩，应此用see sb. doing sth句型。