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 ​ &#