No one this building without the permission of the police . A is leaving B is to leave C

问题补充：

No one this building without the permission of the police .

A is leaving B is to leave C has left D will be leaving

答案：

解析：考察be to do 用法。Be to do用于否定句，表示“禁止”，相当于mustn’t。结合句意可知B正确。句意：没有警察的允许，任何人都不得离开大楼。