In the school hall where a meeting some students are busy preparing for it.A. is held B

问题补充：

In the school hall, where a meeting , some students are busy preparing for it.

A. is held

B. has been held

C. is being held

D. is to be held

答案：

A. is held

B. has been held

C. is being held

(答案→)D. is to be held

解析：考查时态。句意：在在要举行会议的学校大厅里，一些学生们正在忙碌的为此做准备。结合语境可知定语从句中描述的是将来的动作。不定式做表语可以表示计划打算进行的动作，故选D。