多项选择题Whichfourstatementsaretrue?()
A.Has-a relationships should never be encapsulated.
B.Has-a relationships should be implemented using inheritance.
C.Has-a relationships can be implemented using instance variables.
D.Is-a relationships can be implemented using the extends keyword.
E.Is-a relationships can be implemented using the implements keyword.
F.An array or a collection can be used to implement a one-to-many has-a relationship.