题目

The surprising experiment I am about to describe proves that air is all around you and that it proves down upon you. Air pressure is a wonderful force. When you swim underwater, you can feel water push down your body. The air all around you does the same. However, your body is so used to it that you do not notice this. The pressure is caused by a layer of air called the atmosphere. This layer surrounds the Earth, extending to about five kilometers above the Earth’s surface. The following experiment is an easy one that you can do at home. But make sure that you are supervised (监督)列综合算式解答.280除以35与15的差，商是A.14B.20C.8D.18