Hiram Revels,the first black member of the United States Sen

答案：
B
分析：空格前为名词,后面是句子,由此判断空格处缺定语从句引导词.
(A)中which一般做定语从句的主语,从句中有主语是它一般做介词宾语,此时前面缺介词.
(C)(D)中which前面都不是介词,故选
(B).
翻译参考：美国参议院的第一个黑人成员Hiram Revels,作为来自密西西比的参议员,就职于他1870
年时被任命的部门.

Rain tomorrow?
Can I help you?
It"s raining now.
Why don"t you go home?
Why not bring the umbrella?
望有所帮助！

Hiram Revels,the first black member of the United States Senate ,servedas senator from Mississippi,an office _______he was elected in 1870.
A which B to which C and which D at which