有一个交通工具类vehicle，将它作为基类派生小车类car、卡车类truck和轮船类boat，定义这些类并定义一个虚函数用来显示各类信息。(There is a vehicle class vehicle. It is used as a base class to derive car of car, truck truck and ship boat. These classes are defined, and a virtual function is defined to display all kinds of information.)