bicycles = ['trek', 'cannondale', 'redline', 'specialized']

 print(bicycles)

 bicycles.reverse() #倒置原列表,永久性修改列表元素,但可恢复

 print(bicycles)

 bicycles.reverse() #倒置列表,恢复为原列表

 print(bicycles)

 运行结果应该是：

     ['trek', 'cannondale', 'redline', 'specialized']

     ['specialized', 'redline', 'cannondale', 'trek']

     ['trek', 'cannondale', 'redline', 'specialized']