问题
选择题
The engineers made two big plans for the dam, ____ was never put in force.
A．one of them
B．which
C．one of which
D．every one of which
答案
答案：C
本题主要是对句子结构及关系是考查。根据逗号可知，后面句子为非限制性定语从句，先行词是plan；再根据句子中的was及前面的two可知本题的正确答案为C。