一道OG的题目

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 the concept of an age in which great ice sheets had existed in now currently temperate areas.

(A) in which great ice sheets had existed in now 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

答案是B，有点理解不同，（１）in what are now temperate areas ,感觉很罗嗦，要怎么理解．

（２）exist 这个动作发生在led前吧？为什么不用过去完成时而用过去时？

1,固定搭配 age in which,排除CDE

2,now currently 重复，排除A.

3, 所以选B.