请教section 14-13

waitingtoexhale

请教section 14-13

13.   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

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

答案是B。我想请问A中now和currently算不算重复？还有为什么不能用过去完成时？

fchn951

now和currently算重复.另外有关过去完成时，ETS比较prefer用在发生在过去某一时间之前，而且这个过去某一时间一定要在题目中有明确的标志。