问题
单项选择题
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
参考答案：C
解析：
本题主要是对句子结构及关系的考查。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。故选C。