it was...who强调句部分是人用什么,是物呢

英语常用的强调结构是"It is (was)+被强调部分(主语、宾语或状语)+who (that)...".
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.在美国英语中指事物时常用which来代替that.
例句：
原句：My father did the experiment in the lab yesterday evening.
强调主语：It was my father who did the experiment in the lab yesterday evening.
强调宾语：It was the experiment that my father did in the lab yesterday evening.
强调时间：It was yesterday evening that my father did the experiment in the lab.(注意不用when)
强调地点：It was in the lab that my father did the experiment yesterday evening.