e.g. With so much work to do, I'm not able to go to the cinema.

1. 用作独立成分的不定式

e.g. To be frank, I don't agree with what you said.

可做插入语的还有：

to tell you the truth 说老实话 to be frank 坦率地说to begin with 首先 to be brief 简言之

to make a long story short 长话短说 to be exact 精确地说to say nothing of 姑且不说 to conclude 总而言之

to be sure 诚然，固然 to do him justice 说句对他公道的话so to speak 可以这么说

2. 用主动形式表示被动含义

e.g. Do you have anything to say on this question?

The book is difficult to understand.

There is nothing to worry about.

高中阶段常见带介词的to短语归纳：

be/get/become used to 习惯于 be given to 沉溺于

be related to 与...有关系 be addicted to 沉溺于；对...上瘾

be opposed to 反对 devote oneself to献身于；专心于

get down to 着手做 lead to 导致 object to反对；不喜欢；不赞成

put one's mind to全神贯注于 give rise to 引起

look forward to 盼望 pay attention to 注意

stick to 坚持 make contributions to对...作贡献

1. （2014湖南卷）ourselves from the physical and mental tensions，we each need deep thought

and inner quietness.

A. Having freed B. Freed C. To free D. Freeing

答案: C

解析: 不定式做目的状语是不定式的一个经典用法。而且本句的主语we和动词free之间构成主动关系，可以使用不定式或者现在分词。但是A项使用的是不定式的完成式，表示已经完成的动作，这不符合上下文语境。句义：为了让我们免受精神和身体压力的伤害，我们每个人都需要深入的思考和内心的安宁。

2. （2014江西）He is thought ___foolishly .Now he has no one but himself to blame for losing the job.

A. to act B. to have acted C. acting D. having acted