中国石油大学 / 中石油
正确率：100%
20. 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
A、one of them
B、which
C、one of which
D、every one of which
参考答案：
佳题速递：