虚基类：声名一个基类vehicle, 有私有成员MaxSpeed和Weight，公有成员run()和stop(),以及构造和析构函数。

从vehicle派生bicycle和motorcar, bicycle有私有成员height， motorcar有私有成员seatnum,以及各自的构造函数和析构函数。-Virtual base class: The reputation of a base class vehicle, a private member MaxSpeed ​ ​ and Weight, public member run () and stop (), as well as constructor and destructor function. Derived from the vehicle bicycle and motorcar, bicycle, private member height motorcar private members of seatnum, and their respective constructor and destructor.