问题补充:
Look ! The building which now will be used as a library.
A. is being built
B. to be built
C. is built
D. being built
答案:
(答案→)A. is being built
B. to be built
C. is built
D. being built
解析:which now是定语从句,根据now,从句谓语要用现在进行时态,且主语which,即The building,和build是动宾关系,所以用现在进行时态的被动语态。选A。