1.一般情况用It is(was)……that…如：

　　He read three books in the library yesterday.

　　我们分别可以强调主语、宾语、地点状语和时间状语。如：

　　It was he who(that)read three books in the library yesterday.(强调主语)

　　It was three books that he read in the library yesterday.(强调宾语)

　　It was in the library that he read three books yesterday.(强调时间状语)

　　2.当被强调部分指人时，可用that，也可用who；指物时，只用what,如：

　　It was Tom who(that)I met last week.

　　It is a new boke that his brother wants to buy.

　　3.强调状语时，只用that,不用when、where.如：

　　It is at 5 o'clock that the train will arrive.

　　4.被强调的部分是主语时，注意句子的谓语动词和被强调的主语保持一致。如：

　　It is he who is late. 　It is they that were late.

　　5.一般疑问句的强调句为“Is (was) it that…?”；特殊疑问句为：“特殊疑问词 is (was) that…?”结构。如：

　　Was it ten years ago that his father died?（他的父亲是十年前去世的吗？）

　　When is it that you will set off?（你到底什么时候出发？）

　　6.“not…until…”句型的强调结构为“It is not until…that…”应注意把否定词not转移到until前面。如：I didn't go home until rain stopped.(直到雨停了我才回家)。

　　强调句为：It was not until rain stopped that I went home.

　　I didn't know the news until yesterday.(直到昨天我才知道那个消息)

　　强调句为：It was not until yesterday that I knew the news.