证明大气压存在的实验很多 .其中的覆杯实验取材方便 ,操作简单 ,如图 1所示 .但学生往往认为纸片是被水沾住的 .所以对该实验可作如下改进 :图 1　　　　　　　　　图 2　　取一空矿泉水瓶截取瓶口部分约三分之一 ,把截口磨平 ,并在瓶盖上钻一直径约 1毫米的小孔 .实验时 ,用 There are many experiments to prove the existence of atmospheric pressure. Among them, the cup-covered experiment is easy to draw and easy to operate, as shown in Figure 1. However, students often think that the paper is covered by water. Therefore, the following improvements can be made to this experiment: Figure 1 Figure 2 Take an empty water bottle and cut about one-third of the bottle mouth. Grind the cut-off and drill a small hole about 1 mm in diameter on the bottle cap.