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
正确答案是b,只是不明白为什么exist不能用过去完成时,难道这道题这里不应该用过去完成时表示过去发生结束的事情吗?不懂……
[此贴子已经被作者于2006-9-27 21:01:29编辑过] |