问题补充:
The factory was built in a secret place, around high mountains.
A. which was
B. it was
C. which were
D. them were
答案:
A. which was
B. it was
(答案→)C. which were
D. them were
解析:around which were high mountains 是一个由“介词+which”引出的非限制性定语从句,而在该从句中,主语是 high mountains,around which 是表语,所以句子谓语应用复数were,而不是用单数 was。