1.It + 系動詞 + 從句。例句：

1) It seems that your brother might change his mind/he enjoys it very much．看來你哥哥

可能改主意了/他非常喜歡這個。

2) It looks as if we're going to have trouble with them again/it is going to rain．

看起來我們又有麻煩了/天要下雨了。

2.It + 感官動詞。例句：

1) It looks like a robot/man/fish．

這看起來像個機器人/人/一條魚。

2) It tastes delicious/terrible/salty．

這吃起來味道不錯/很差/太咸了。

3) It smells good/bad/sweet．

聞上去不錯/很糟/很清香。

4) It feels cold outside．/ It feels hard/soft．

外面感覺很冷。/摸起來感覺很硬/軟。

3.It is time to do sth./for sth．例句：

1) It is time to have supper/go to bed/watchTV．

該吃晚飯/睡覺/看電視了。

2) It is time for supper/bed/break/my class．

該吃晚飯/睡覺/休息一會兒/上課了。

4.It is (high) time that...(用虛擬語氣表達看法)，

例句：

1) It is time that we went off/we went to school．

我們該告辭/上學去了。

2) It is high time that we reformed our educational systems/I was off．早就該改革我們的教育體

系了/我早就該告辭了。

5.It is + 形容詞 + (for sb.) to do sth. (It作形式

主 語，代替后面的動詞不定式短語to do sth.)，

例 句：

1) It is better(for you) to do some reading on rainy days/wait and be safe．下雨天(你)最好讀點書/(你)最好等著并注意安全。

2) It is easy to get lost in a big city like Tokyo/B-eijing/New York．在東京/北京/紐約這樣的大城市很容易迷路。

3) It is hard to say because I like many films/I don't know much about pop music．

這很難說， 因為我喜歡的電影很多/我對流行音樂不太了解。

4) It is interesting to hear about your soccer team/your school band．很有意思聽到關(guān)于你們足球隊/校樂隊的消息。

6.It is + 形容詞 + V + ing (It作形式主語，代替后面的動名詞短語)，例句：

1) It is good for health doing some exercises ev-eryday. 每天鍛煉身體有益于健康。

2) It is useless (no use) talking about it.

談?wù)撨@個沒有用。

7.It is + 過去分詞 + that... (It代替后面的主語 從句)。例句：

1) It is well-known that two thirds of the earth is covered with water．

眾所周知，地球的2/3被水覆蓋。

2) It is said/reported/believed that Christopher Columbus is the first man to discover the A-merica．據(jù)說/據(jù)報道/據(jù)信克里斯托夫· 哥倫布是發(fā)現(xiàn)美洲的第一人。

8.It is + 形容詞 + that...(用虛擬語氣表達對某事物的看法，It代替后面的主語從句)例句：

1) It is important that theory (should) be closely combined with practice.

理論緊密聯(lián)系實際是重要的。

2) It is strange that she (should) have left with the lights still on．

真奇怪，她怎么讓燈亮著就走了。

9.It作形式賓語。例句：

1) We think it necessary to practice oral English every day．

我們認為每天練習英語口語很有必要。

2) They consider it useless learning so many wo-rds by heart without knowing how to use them.

他們認為記那么多單詞而不知如何使用是沒有用的。

10.It is (was) + 被強調(diào)部分 + that +what/w-hich/who /whom/whose+句子的其他成 分。例句：

1) It is Mary that (who) does the experiment in the factory every day．

是瑪麗每天在工廠做實驗。(強調(diào)主語)

2) It is the experiment that (which) Mary does in the factory every day．

瑪麗每天在工廠做的是實驗。(強調(diào)賓語)

3) It is the factory that Mary does the experi-ment in the factory．

瑪麗每天是在工廠做的實驗。(強調(diào)地點狀語)

4) It must be Tom that is listening to the music.肯定是湯姆在聽音樂。

(用情態(tài)引詞，強調(diào)主語)

5) It was not until dark that he realized it was too late to return home. 直到天黑，他才意識到太晚了。(強調(diào)時間狀語)

11.it用來表示天氣、自然環(huán)境、時間或距離。例句：

1) It is getting warmer day by day．

天氣一天天地暖和起來。(表天氣)

2) It isquite dark in the room．

房間里很暗。(表光線)

3) It will be spring soon．

馬上就是春天了。(表時間)

4) How far is it from here to the station?

從這里到火車站有多遠?(表距離)