Answer:
A. Features that member functions are overloaded:
(1) the same range (e.g. in the same class);
(2) The function name is the same;
(3) different parameters;
(4) virtual keyword is optional.
B. Overlay refers to a derived class function that overrides a base class function, characterized by:
(1) different ranges (in derived classes and base classes, respectively);
(2) The function name is the same;
(3) the same parameter;
(4) The base class function must have the virtual keyword.
C. " Shadowing refers to a function of a derived class that masks a base class function with the same name as the following rule:
(1) If the function of the derived class has the same name as the function of the base class, but the parameters are different. At this point, the function of the base class is hidden, regardless of the virtual keyword (Note that you are not confused with overloading).
(2) If the function of the derived class has the same name as the function of the base class, and the parameters are the same, the base class function does not have the virtual keyword. At this point, the function of the base class is hidden (note that it is confused with overrides)
Hiding destroys polymorphism, so you typically replace it with overwrite.