A cup--shaped rubber sucker is placed over the plug- hole and pressed down so that the rubber end is squashed flat; then it is released and springs back into its usual cup shape, drawing the air back with it.

• 把帽盖形的橡皮吸头放在堵塞的洞口上，往下压，带橡皮的那头就会压扁，然后松开，弹回到它平常的帽盖形，空气随之抽回。