2.Many new buildings have been set up in our city ______.共两题类似题目

2.Many new buildings have been set up in our city ______.共两题类似题目
2. Many new buildings have been set up in our city ______.
A. since five years B. in five years
C. in 2008D. in the past five years
这道题目语法点?为什么不选D?
4. The ______ teachers wondered if the ______ students were in trouble.
A. women; boyB. woman; boys
C. women; boysD. woman; boy
为什么不选A?原因?
谢谢