When a tornado destroys a house, it doesn’t blow it down the way a hurricane（十二级台风）does. It makes the house explode（爆炸）. When air that surrounds a house presses against it all time, it usually has a force of about 15 pounds per square inch. The air inside the house presses out against the walks just as hard. When a tornado passes over a house, it suddenly sucks away the air outside the house. The air inside the house still pushes out against the walls. But now there is nothing pushing back. So the walls are pushed out in an explosion. Pieces of the house are sucked up into the tornado and carried away. There is little left where the house once stood.

A．air pushes from the outside

B．air pushes from the inside

C．there is a different kind of pressure

A．greater than the air pressure inside

B．the same as the air pressure inside

C．less than the air pressure inside

A．the air outside is taken away

B．the air inside is taken away

C．too much air is pushing outside

A．as if there had been a fire

B．like a pile of wood

C．as if a bomb（炸弹）had exploded in it