This afternoon there will be a fire drill. Now please remember the instructions. When the

bell rings, you all go very quickly, in an orderly way, down the stairs—the stairs, remember, not in the lifts(电梯). I repeat, do not use the lifts—and assemble in the square outside. You can come into the building again once the signal has been given.

A fire drill is______.

A．a real fire

B．to drill for fire

C．to put out fire

D．to prepare people for a real fire