The building will be used as our new library.
A. is being constructed
B. built
C. under construction
D. to build
网友回答
A. is being constructed
B. built
(答案→)C. under construction
D. to build
解析：本题考查非谓语动词和介词短语。句中已经有谓语，这里要用短语作定语修饰the building，排除A。根据语境，应该表示在建或要建的大楼，排除B(过去分词表示已经建好的)。D选项应该用被动语态。under construction正在建设中。