一、 不定式的时态
不定式常用的时态有一般式、完成式、进行式和完成进行式四种，常用的为前三种。 1. 一般式(to do)
动词不定式的一般式表示不定式的动作或状态与谓语动词所表示的动作同时发生或在之后发生。如：
I plan to attend the meeting. 我计划参加这次会议。 2. 完成式(to have done)
不定式的完成式表示不定式的动作发生在谓语动词表示的动作之前。如：
（1）I am sorry to have kept you waiting. （2）I hope to have finished the work by now （3）I’m sorry to have given you so much trouble
（4）He seems to have caught a cold.
（5）You appear to have travelled quite a lot （6）I’m pleased to have been given this opportunity
3. 进行式(to be doing)
不定式的进行式表示不定式的动作与谓语动词
所表示的动作同时发生。如：
（1）He seems to be saying something （2）He seems to be eating something. （3）It’s nice to be sitting here with you （4）He is thought to be hiding in the woods
4. 完成进行式(to have been doing)
（1）He is said to have been working in that factory for twelve years.
据说他已在那家工厂工作12年了。
（2）She is known to have been working on the problem for many years
二、 不定式的被动语态（to be done）
（1）It’s a great honour to be invited to the banquet
（2）It’s a pity to be kept in the house in fine weather
（3）All this is to be sold
（4）Water must be pure if it is to be drunk
（5）She doesn’t want to be separated from him （6）I don’t wish to be interrupted in my work （7）She can’t bear to be laughed at
（8）There are twenty more trees to be planted （9）There was a lot of rubbish to be got rid of （10）The Blacks are the first to be fired and the last to be hired
（11）She got there only to be told that they had gone on holiday
（12）I had to shout to be heard
（13）The case was too heavy to be carried by a child
（14）He ordered the goods to be sent by air （15）The books are not allowed to be taken out of the room
4）不定式动词在介词but, except, besides后面时，如这些介词前有实义动词do的各种形式，则后接不带to的不定式，否则带to。如： I have no choice but to accept the fact. 除了接受这个事实我别无选择。 What do you like to do besides swim? 除了游泳你还喜欢做什么？
应当注意，这种不定式很多和它修饰的词有动宾关系(如前四类中的多数句子)。因此，如果这个不定式是不及物动词，它后面就应有必要的介词，如：
She has a lot of things to attend to. 她有很多事要管。
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