强调句是一种修辞，是人们为了表达自己的意愿或情感而使用的一种形式。 我们常用It is/was… who/that结构来突出强调句子的某一成分(一般是句子中主语，宾语或状语)。使用强调句型有几个需要注意的事项：
1.被强调成分是主语，who/that之后的谓语动词应该在人称和数上与原句中的主语保持一致。
e.g. It is I who am right.
e.g. It is he who is wrong.
e.g. It is the students who are lovely.
2.被强调成分是作主语的代词，用主格，是作宾语的代词，用宾格
It was he that helped me yesterday. It was me that he helped yesterday.
3.如果被强调的成分有同位语，同位语也应提前。
It was from him，his chemistry teacher，that Paul learned to watch carefully in class.
4.被强调部分既包括人又包括物，用that不用who
lt was the things and people that they remembered that they were talking about.
5.即使被强调成分是句子中的时间状语，地点状语，原因状语等，也不能用when，where, because，要用 that。
E.g. It was after the war was over that Einstein was able to come back to his research work again .
E.g. It was in front of the bank that the old lady was robbed.
E.g. It was because of the heavy rain that he came late.