题目内容

有如下程序：#includeusing namespace std;class Instrument{public:virtual void Display( )=0;};class Piano: public Instrument{public:void Display( ){/函数体程序略/}};int main( ){Instrument s;Instrument *p=0;//．．．;return 0;}下列叙述中正确的是。

A. 语句“Insturment *p=0;”编译时出错
B. 语句“Instruments;”编译时出错
C. 类Piano中的Display函数不是虚函数
D. 类Instrument是一个虚基类

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