After a fire broke out in the lab,a lot of equipment _________.   [ ]

A.is damaged                  

B. had damaged    

C. damaged                    

D. was damaged

有以下程序；
#include ＜iostream＞
using namespace std;
class R

public:
R(int r1,int r2)

R1=r1;
R2=r2;

void print();
void print () const;
private:
int R1, R2;
;
void R::print ()

cout＜＜R1＜＜","＜＜R2＜＜endl;

void R::print() const

cout＜＜R1＜＜", "＜＜R2＜＜endl;

int main ()

R a(5,4);
const R b(20,52);
b.print();
return 0;

执行后的输出结果是

A．5,4

B．20,52

C．0,0

D．4,5