By the time you get to Greenwich you__ the most historic parts of London.

题目

By the time you get to Greenwich you__ the most historic parts of London.
A.will be seeing B.will see C.are going to see D.will have seen
求每个选顶的解释

答案

正确答案：选D.will have seen
即：By the time you get to Greenwich you will have seen the most historic parts of London.
翻译：你一到格林尼治你就已经看到伦敦最具有历史意义的地区了.
解析：看一下下面几个例句
1 By the time she COMES tomorrow,we will have done our work.(将来)
2 By the time she CAME last week,they had done the work.（过去）
3 By this time(=now) ,all the students HAVE gone home (到眼下)
所以如果by the time后面接的表示将来的时间,那么主句用将来完成时,所以选D
有不明白的请继续追问,