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D，错选了B。BD纠结，不知道该如何判断。第二遍做这道题还是把握不好句意，麻烦老师讲解。