11) It is + adj.+ that 从句 （形容词有：
important, necessay, impossible,
natural等，that•从句中通常用虚拟 语气should do或do）.
It is important that we should keep the balance of nature.
We took it for granted that he would go to the party.
5.用于强调句型：It is/was+ 被强 调部分＋that.
We called on Prof. Wang at his office this morning. It was we that/who called on Prof. Wang at his office this morning. It was Prof. Wang that/who we called on at his office this morning.
6) It doesn't matter to sb. whether...句型：
It doesn't matter to me whether he comes or not.
7)It is said/supposed/known/reported
/announced/ decided等动词＋that句：
用of。
It is necessary for us to master a foreign language. It is very kind of you help me with my English.
5) It happens/seems等动词＋that从句：
It happened that I wasn't there that day. •It seemed that he had read the report.
4) It is ＋ for/of sb. to do sth. (necessary,
important, strange, natural, 后用 for, 在foolish, kind, nice, clever, silly, stupid, good, right, wrong rude等后
It was at his office that we called on Prof. Wang this morning.
It was this morning that we called on Prof . Wang at his office.
用于习惯用语中
1) It takes sb. some time to do sth. It took the sixth blind man quite a long time to find the elephant. 2) It is one's duty to do sth. It is our duty to attend this matter. 3) It is no use /good doing sth. It's no use talking about it.
It is said that the novel has been translated into several foreign languages.
8) It is + 时间 + since从句（从句中 谓语动词用一般过去时）。
It is ages since I last saw him.
9) It is + the 序数词 + time + that从句 （从句中通常用现在完成时）。
４、代替一个不定式、动名词短语或主 语从句。
It is very portant to follow the rules.
It is no use reading without understanding.
It is uncertain when we will finish our experiment. They found it difficult to deal with such a problem.
It/This is the second time that I have been to Beijng.
10) It is + n. + that 从句 （名词有：a pity, a shame, no wonder等）
It is a pity that you didn't come yesterday.
代 词 IT 的 用 法
1.起人称代词的作用，指一个人或 事物；有时用来代替小孩或婴儿.
That is wrong, and he knows it. The sun looks like a shiny gold plate, but it is really a big ball. She is holding a baby in her arms and it was crying.
12) It is time that从句（从句中虚拟 语气did）.
••It is time (that) you went to bed.
13)It is (not) long before从句（从句中 用一般现在时代替一般将来时）。
It will not long before we can have a trip to the moon. It was not long before they drove the invaders from their country.
2.代替前面所提到的一件物、事或人。
The students have saved my life; I shall never forget it. I like skating. It keeps me fit.
３.表示时间、天气、距离、季节事 物的状态和自然环境等。
It will be cold. It is going to snow. It is half past twelve. It is only 5 kilometers to the university. It was early autumn. It was 15℃ yesterday.