英语常用的强调结构是:It is (was) +被强调部分+ that (who) +句子的其他成分。
一般说来,被强调部分指人时,用who;指事物时用that,但that也可以指人。
举个例子：原句：Tom found my pen in the classroom yesterday. 
强调主语：It was Tom who / that found my pen in the classroom yesterday. 
强调句有一个特点就是：去掉It is (was)和that (who) ，剩下的部分是一个完整的句子。
祝学习进步Y(^_^)Y