设顺序循环队列Q[0：M-1]的头指针和尾指针分别为F和R，头指针F总是指向队头元素的前一位置，尾指针R总是指向队尾元素的当前位置，则该循环队列中的元素个数为（   ）。 A.
R-F B.
F-R C.
(R-F+M)％M D.
(F-R+M)％M

多项选择题下列破坏中，属于表面损坏类的有（ ）。A. 错台B. 露骨C. 起皮D. 唧泥

单项选择题About “class” and “object”, which one is incorrect? A、Classes help achieve data abstraction and encapsulation. B、Class contains member functions and member data. Access specifiers in C++ can only be public or private. C、An object is known as instance of a given class. D、Once a class is declared, the class name becomes a type name and can be used to declare variables.