（）常用于3m以下或普通半高矮隔断。

A．小木方双层结构

B．大木方双层结构

C．小木方单层结构

D．大木方单层结构

使用VC6打开考生文件夹下的工程test25_1，此工程包含一个源程序文件test25_1.cpp，但该程序运行有问题，请改正程序中的错误，使程序的输出结果如下：
privatel from derived1:30
privatel from derived2:30
源程序文件test25_1.cpp清单如下：
/***************found******************/
include＜iostream.h＞
class base

protected:
int privatel;
public:
base(int p)privatel=p;
;
/****************found*******************/
class derived1:public base

public:
derivedl(int p1):base(p1);
int get_private()return private1;

class derived2:virtua1 public base

public:
derived2(int p2):base(p2);
int get_private()return private1;
;
class derived12:public derived1,public derived2

public:
/****************found*******************/
derived12(int p1,int p2,int pb):derived1(p1), base(pb), derived2(p2);
;
void main()

derived12 d(10,20,30);
cout＜＜"privatel from derived1:"＜＜d.derived1::get_private();
cout＜＜"\nprivatel from derived2:"＜＜d.derived2::get_private();
cout＜＜endl;