The scientist has made another discovery, I believe is of great importance.
A. that B./ C. which D. why
The factory was built in a secret place, around high mountains.
A. which was B. it was C. which were D. them were
对于非限制性定语从句考查中句中出现逗号的情况,首先看逗号旁是否有连词,没有连词就意味着逗号前后内容一定有一部分是完整的句子,另一部分是修饰成分或非限制性定语从句。第一道题显然逗号后为非限制性定语从句,对discovery进行修饰,选which;第二道题逗号后为非限制性定语从句,介词around前置,句序还原为high mountains …around which(a secret place),be动词跟mountains一致为复数。