What are the police doing there? —They are _______ the building. A robber ran into it just now.

______ are the animals sleeping in the cages every day?—It’s about ten hours. [ ]

Is this the reason _____ at the meeting for his carelessness in his work?

Greatly frightened by the terrible scene, _______.

In fact he knows this place very well, for he ________ there three times.