12. It be…before…

该句型主句中的it指时间，主句中的时态常是一般将来时或过去时两种时态，主句中的表语多是long ,not long ,3 days, 2 weeks等表示时间段的词和短语。常译为“…之后才”，“没过……就……”

It was 3 days before he went to Beijing.

It will not be long before he finishes his job.

13. It happens (seems, looks, appears) that…

该句型中的it 是形式主语，that 引导的是主语从句，主句中的happen, seem等词是不及物动词。

It happened (so happened) that he met his teacher in the street. (碰巧……)

It seems that he will be back in a few days. (看来……)

The Foreign Minister said, “___our hope that the two sides will work towards peace.” (2004北京)

A. This is B. There is C. That is D. It is (D)

14. It takes sb…to do sth.

该句型中的不定式是真正的主语，是形式主语，句型中的直接宾语是时间。常译为“做……要花费某人……”

It took thousands of people many years to build the Great Wall.

15.It is no good (use) doing sth.

该句型中的真正主语是动名词短语，主句中的表语可以是 no good (not any good), no use (not any use ).

It is no good learning English without speaking English.

16. It doesn’t matter whether…

该句型中的引导的从句是真正的主语，该句型译为“不论(是否)……没关系……

It doesn’t matter whether they are old.

17.It is kind (of sb) to do sth.

该句型中的不定式短语是真正主语，如果不定式的逻辑主语是由of引出，主句中的形容词必须是能表示逻辑主语的形容词。常见的有：bad, brave, careless, clever, cruel, foolish good (好心的),honest, horrible, kind, lazy, modest, naughty, nice (有教养的),polite, rude, silly, stupid ,wise ,wrong等。这个句型可以改写为sb.is kind to do sth.

It is kind of you to stay so =You are kind to say so.