It’s the first time he has helped us.A. that B. before C. whenD. who

问题补充：

It’s the first time he has helped us.

A. that

B. before

C. when

D. who

答案：

(答案→)A. that

B. before

C. when

D. who

解析：考查连词。本题考查强调结构it’s … that …，强调状语the first time，故选A。