The building will be used as our new library.A. is being constructedB. builtC. under con

问题补充：

The building will be used as our new library.

A. is being constructed

B. built

C. under construction

D. to build

答案：

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thebuilding，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。