May I come in? I’m sorry I’m late.—Come in, please. But could you tell me ?

I will stay at home and read some books if it _________ tomorrow.

Excuse me. Where is Mr Green’s office?—It’s on ______ floor.

The number of giant pandas is getting _________ because their living areas are becom­ing farmlands.

You can hardly imagine what great difficulty we had _________ the task.