自行车在中国很受欢迎，骑车上学或上班都很方便，但现在越来越多的人......。这使得......。而骑车既可以......，又可以......。那么你更喜欢哪种交通工具呢？为什么？ Bicycles are very popular in China. It's convenient to ride them to go to work or school . But now more and more people have cars. That makes those people have less physical activities. While bike-riding gives people not only convenience but also chance to do exercises. Which vehicle do you prefer? Why?