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)