By the middle of the 21st century ,the vast majority of the world's population _ in the cities rather than in the country.A.are living B.will be living C.have lived D.will have lived
问题描述：
By the middle of the 21st century ,the vast majority of the world's population _ in the cities rather than in the country.
A.are living B.will be living C.have lived D.will have lived
答
B, 将来进行时时 ；表示将来某时进行的状态或动作,或按预测将来会发生的事情；21世纪中叶，现在还没到， 对将来居住地人口情况的预测。
答
将来时态，D将来完成时态
答
答案：B
解释：
1、由于时间状语是将来的,所以用一般将来时,排除C.
2、答案A are要改成 is,所以A 排除.
3、will have lived 表示“将已经居住在”,是完成时.
4、will be living 用的是一般将来时的进行时.
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