如图所示，某同学将空的金属筒开口向下压入水中．设筒内空气无泄漏，不计气体分子间相互作用，被淹没的金属筒在下降过程中，筒内空气体积减小．则筒内空气的压强如何变化？试从分子热运动的角度进行解释．

   Of all the things we eat and drink，water is the1important.The human body can go2 food for a long time，but two3three days without water could make people4.
   A lot of people don't understand how5water the human body needs6well and many people don't drink enough，esecially in7weather. Most people drink8they are thirsty but in fact they need more water，expecially when they take9.A man's body is 65 to 75 percent of10. If we don't have enough water. We fell tired and may become ill.