Question

Obama,  _______  life was once hard when he was young, were elected President of American.

A．for whom

B．who

C．to whom

D．/

Answer 1

A

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。