it is that 强调句用法如下：
当需要强调句中的主语，宾语和状语时，常用强调句：it is/was+ 被强调的部分 ＋that/who.
He bought three books in the bookstore yesterday.
强调主语：
It was he that/who bought three books in the bookstore yesterday.
强调宾语：
It was three books that he bought in the bookstore yesterday.
强调状语：
It was in the bookstore that he bought three books yesterday.
扩展资料
1、陈述句的强调句型
It is/ was + 被强调部分（通常是主语、宾语或状语）+ that/ who（当强调主语且主语指人）+ 其他部分。
例如：It was yesterday that he met Li Ping. 昨天他遇到了李平。
2、 一般疑问句的强调句型
It is/ was + 被强调部分（通常是主语、宾语或状语）+ that/ who（当强调主语且主语指人）+ 其他部分。同上，只是把is/ was提到it前面。
例如：Was it yesterday that he met Li Ping? 昨天他遇到了李萍吗？
3、特殊疑问句的强调句型
被强调部分（通常是疑问代词或疑问副词）+ is/ was + it + that/ who + 其他部分？
例如：When and where was it that you were born? 你何时何地出生？
4、not … until … 句型的强调句
句型为：It is/ was not until + 被强调部分 + that + 其他部分；此句型只用until，不用till。但如果不是强调句型，till, until可通用；因为句型中It is/ was not 已经是否定句了，that后面的.从句要用肯定句，切勿再用否定句了。
普通句：He didn't go to bed until/ till his wife came back. 强调句：It was not until his wife came back that he went to bed.
5、谓语动词的强调
It is/ was ... that ... 结构不能强调谓语，如果需要强调谓语时，用助动词do/ does或did.
例如：Do sit down. 务必请坐。Do be careful when you cross the street. 过马路时，务必（千万）要小心啊！
此种强调只用do/ does和did，没有别的形式；过去时用did，后面的谓语动词用原形。
It叫做强调it，is后面是要强调的部分，that后面是句子的剩余部分。例如：He helps me with my maths.（他帮助我学习数学。）对主语He强调，写成：It is he that helps me with my maths.