江苏省某出版社１９９９年版《新编初中物理试卷》有这样一道题：给自行车内胎打气，起初空气很容易压入车胎．可是到后来就不容易了，试用分子运动论的观点解释这一现象． 该书提供的答案是：这是因为随着空气不断地被压入车胎后，车胎内空气分子间的距离不断减小，分子间的作 A 1999 edition of the “New junior high school physics paper” published by a publishing house in Jiangsu Province has such a question: Inflate the bicycle inner tube. At first, the air is easily pressed into the tire. But later it was not easy, and the idea of ​​molecular movement theory was used to explain this phenomenon. The answer provided by the book is: This is because as the air is continuously pressed into the tire, the distance between the air molecules in the tire is continuously decreasing, and the intermolecular distance is reduced.