It作形式主語是中學階段英語學習的主要語法項目之一，因此要懂得如何使用，以下是由學習啦小編整理關于形式主語it的用法的內容，希望大家喜歡!

　　形式主語it的用法

　　當不定式(短語)、動名詞(短語)或從句在某個句子中作主語時，為保持句子結構前后平衡，避免頭重腳輕，因此常用it作形式主語置于句首，而將真正的主語放在句尾。此時it只起先行引導作用，本身無詞義。

　　e.g. It is wrong to tell a lie.

　　(說謊是錯誤的。) 〔It為to tell a lie的形式主語〕

　　It is no use arguing about it.

　　(爭吵是沒用的。) 〔It為arguing about it的形式主語〕

　　It is uncertain who will come.

　　(誰要來還不確定。) 〔It為who will come的形式主語〕

　　It 作形式主語的常見句型：

　　① It + be + 形容詞 + to do sth. / doing / that ….

　　e.g. It is very important to learn a foreign language.

　　(學一門外語非常重要。)

　　It is useless crying over the spilt milk.

　　(覆水難收。)

　　It was really surprising that she married a man like that.

　　(她嫁給那樣的男士真讓人驚訝。)

　?、?It + be +名詞詞組 + doing / that ….

　　e.g. It is no good telling lies.

　　(撒謊沒好處。)

　　It is a pity that you didn’t go to see the film yesterday.

　　(你昨天沒看成那部電影真遺憾。)

　　It is a truth that there would be no new China without the Communist Party.

　　(沒有共產黨就沒有新中國，這是毋庸質疑的。)

　?、?It + be + 過去分詞 + that ….

　　該句型常見動詞有：say, hope, think, suppose, expect, report, know, believe, decide, etc.

　　e.g. It is said that they have invented a new type of computer.

　　(據(jù)說他們發(fā)明了一種新型電腦。)

　　It is believed that China will become one of the strongest countries in the world.

　　(大家都相信中國將會步入世界強國之列。)

　　It was reported that more than 170 thousand people died in the 2004 tsunami.

　　(據(jù)報道，至少有十七萬人在2004年那場海嘯中喪生。)

　　④ It + seems / appears / happens等不及物動詞 + that ….

　　e.g. It seems that he enjoys pop songs very much.

　　(似乎他非常喜歡流行歌曲。)

　　It appears that Tom might change his mind.

　　(看來湯姆可能會改變主意。)

　?、?若句子是疑問形式，就只能用it作形式主語。

　　e.g. Does it matter much that they won’t come tomorrow?

　　(他們明天不來很重要嗎?)

　　Is it true that he will go abroad next week?

　　(他下周出國是真的嗎?)

　?、?It + takes + (sb.) + some time + to do sth.

　　這是一個表示“(某人)花多少時間干某事”的句型，其中it是形式主語，代替后面的不定式(to do sth.)，句型中的sb.也可以省略。

　　e.g. It took me some time to read the reading materials.

　　(我花了一些時間才讀完那段閱讀材料。)

　　It took him fourteen hours to go to New Zealand from Shanghai by plane.

　　(從上海乘飛機去新西蘭花了他14小時。)

　　How long does it take you to go to Beijing from Qingdao by train?

　　(從青島坐火車到北京一般要花多久時間?)

　　I am not sure, but I think it takes at least nine hours to get there.

　　(我不能肯定，但估計至少要九個鐘頭才能到那兒。)