[译文] 希拉姆• 赖尔斯是美国参议院的第一位黑人议员，1870年他当选为密西西比州参议员。
(1) 画线部分错误分析。
本题的考点有两处：①动词elect的搭配；②介词+ which引导的定语从句。主句中的 the first black member of the U.S. Senate 是 Hiram Revels 的同位语，an office where he was elected in 1870是 senator的同位语，即 an office指 senator这个职位，所以正确的 搭配应该是 he was elected to the (an) office。
(2)选项分析。
根据上述分析，本题考查动词elect的搭配，根据elect ...to (as )的固定用法，A 、B、 D 选项均可排除。此外，本题还涉及定语从句中“ 介词+ 关系词which” 代替where 的用法，an office to which he was elected in 1870 有时也可替换为 an office where he was elected in 1870，但后者有歧义，where还有可能是in which，与本句的语义不一致。