Obama, life was once hard when he was young, were elected President of American.
A. for whom
B. who
C. to whom
D. /
网友回答
(答案→)A. for whom
B. who
C. to whom
D. /
解析：这是一个非限制性定语从句，还考查到了“介词+关系代词”引导的定语从句。根据句子意思需选择介词for, 从而构成be hard for Obama. for的宾语是指人，这时就只能用whom。