The first thing we should do is to tell him the news.A. whoB. whichC. thatD. whom

问题补充：

The first thing we should do is to tell him the news.

A. who

B. which

C. that

D. whom

答案：

A. who

B. which

(答案→)C. that

D. whom

解析：句意：我们应该做的第一件事情是告诉他这个消息。结合语境可知 本句中先行词the first thing为下文的逻辑宾语，指物且前面有序数词first修饰，故引导词只能用that，选C。