今天小编带大家来复习一下英语三级中 It的用法
(1)用作形式主语

　　It is difficult to translate this article. 翻译这篇文章很难。

　　It is getting harder every day for a lazy man to get a living. 懒汉谋生是日益困难了。

　　What time would it be most convenient for me to call again? 什么时候我再给你打电话最合适?

　　It is no use going there so early. 这么早去那里没有用。

　　It has been a great honour your coming to visit me. 你的来访是我很大的荣幸。

　　It is strange that he did not come at all. 真奇怪，他竟还没来。

　　It doesn’t matter what you do. 什么都没关系。

　　在上述诸例中，后置的真正主语可以取代先行it的位置，而出现于句首。

　　To translate this article is difficult.

　　Going there so early is no use.

　　That he did not come at all is strange.

　　上述结构远不如用先行it结构普通。此外，也并非所有先行it结构都可作上述转换。如：

　　It seems that John is not coming after all. 似乎约翰终竟不来。

　　It happened that John was the only witness. 碰巧约翰是唯一的证人。

　　上述两例只能转换为：

　　John doesn’t seem to be coming after all. John happened to be the only witness.

　　(2)用作形式宾语

　　I found it difficult to explain to him what happened. 我觉得向他解释清发生了什么事很困难。

　　He thought it no use going over the subject again. 他认为再讨论这个问题没有用了。

　　They kept it quiet that he was dead. 他们对他的死保密。

　　We must make it clear to the public that something should be done to stop pollution. 我们必须使公众明白应该采取措施制止污染。

　　(3)注意以下几种强调句的翻译：

　　It was Jane that/who called this morning. 是珍妮今天上午打来电话。

　　It was a parcel that she brought him. 她带给他的是一个包裹。

　　分别强调主语、间接宾语、直接宾语、状语，使之成为信息中心。

　　It was John that/who gave Mary a handbag at Christmas. 是约翰在圣诞节给了玛丽一个提包。

　　It was Mary that John gave a handbag (to) at Christmas. 约翰在圣诞节是给玛丽提包的。

　　It was a handbag that John gave Mary at Christmas. 约翰在圣诞节给玛丽的是一个提包。

　　It was at Christmas that John gave Mary a handbag. 是在圣诞节约翰给了玛丽一个提包。

　　It was when she was about to go to bed that the telephone rang. 是在她即将上床睡觉时电话铃响了。

　　It was because I wanted to buy a dictionary that I went to town yesterday. 我昨天是由于想买一本词典而进城的。

　　It was not until his father came back that Tom went to bed yesterday. 昨天汤姆是直到他父亲回来才上床睡觉的。(注意句中not的位置).