1. The factory was built in a secret place, around _________ high mountains.
A. which was B. it was C. which were D. them were
【陷阱】容易误选A或B，将A、B中的 which 和 it 误认为是其后句子的主语。
【分析】最佳答案是C，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。请做以下类例题目（答案均为C）
