ClassA是一个类，且有如下语句序列ClassA c1,*c2;ClassA *c3=new MyClass;ClassA &c4=c1;则ClassA的构造函数被调用的次数是

单项选择题有如下程序：#include#includeusing namespace std;class Animal{public:virtual string GetType() const { return Animal ; }virtual string GetVoice() const { return Voice ; }};class Dog:public Animal{public:string GetType() const { return Dog ; }string GetVoice() const { return Woof ; }};class Cat:public Animal{public:string GetType() const { return Cat ; }string GetVoice() const { return Miaow ; }};void Type(Animal& a) { cout<<a.GetType(); }void Speak(Animal& a) { cout<<a.GetVoice(); }int main() {Dog d; Type(d); cout<< speak ; Speak(d); cout<< - ;Cat c; Type(c); cout<< speak ; Speak(c); cout<<endl;return 0;}运行时的输出结果是

单项选择题执行语句序列 int n=0; for (int i=60; i>0; i-=3) n++;之后，变量n的值是