[求助]og 59

In OG 11th

59. His studies of ice-polished rocks in his Alpine homeland, far outside the range of present-day glaciers, led Louis Agassiz in 1837 to propose* concept of an age in which great ice sheets' had existed in now currently temperate areas.

A) in which great ice sheets had existed: currently temperate areas

(B) in which great ice sheets existed in what are now temperate areas

(C) when great ice sheets existed where there were areas now temperate

(D) when great ice sheets had existed in current temperate areas                    （B）

(E) when great ice sheets existed in areas now that are temperate

Why does it use past tense "existed", not past perfect "had existed"?

up

By the time L proposed xxx  I think the ice sheet had already disapeared.

So the past perfect verb form shows the order of two events took place in the past.

这是过去时态和过去完成的区别.

. His studies of ice-polished rocks in his Alpine homeland, far outside the range of present-day glaciers, led Louis Agassiz in 1837 to propose* concept of an age in which great ice sheets' had existed in now currently temperate areas.

很明显,句子的主语是his studies,谓语是led  (to),

谓语动词用的是一般过去时态

我们在使用过去完成时态一般指的是过去的过去,就与定语从句所修饰的age想矛盾拉

黄色部分不太明白啊