衍生类别中的函式试图覆写基底类别中的虚拟函式，但衍生类别函式没有与基底类别函式相同的传回型别。

A function in a derived class attempted to override a virtual function in a base class, but the derived class function did not have the same return type as the base class function.

youdao

由抽象类别衍生出来的类别必须实作纯虚拟成员函式，否则它们也是抽象类别。

Classes derived from the abstract class must implement the pure virtual member function or they, too, are abstract classes.

youdao

由抽象类别衍生出来的类别必须实作纯虚拟成员函式，否则它们也是抽象类别。

Classes derived from the abstract class must implement the pure virtual member function or they, too, are abstract classes.

youdao