It was last night I saw the comet.A. the timeB. whenC. thatD. which

问题补充：

It was last night I saw the comet.

A. the time

B. when

C. that

D. which

答案：

A. the time

B. when

(答案→)C. that

D. which

解析：强调句的结构是：It＋be＋强调部分＋that(who)＋主谓句。强调句的连词只有两个，that和who。当强调的部分是人，且为句子的主语时，才用“who”，其余用that。