再如：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. （注意不用where）