阅读程序,写出运行结果。#include using namespace std;class TT{private:int k;public:static int n;TT(int kk=0){k=kk;n++;}void Display( ){cout<<"n="<
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阅读程序,写出运行结果#include#includeclass point;//前向声明point类class A{public:double distance(point &p1,point &p2);//...};class point{private:double x,y;public:point(double xx=0,double yy=0) {x=xx;y=yy;}double get_x( ) {return x;}double get_y( ) {return y;}friend double A::distance(point &p1,point &p2); //A类的成员函数作point的友元};double A::distance(point &p1,point &p2){return (sqrt((p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y)));}void main( ){point myp1(1,1),myp2(4,5);A obj;//必须声明一个A类的对象cout<<"Thedistance is:"<
用活性炭脱色时,为什么要待固体物质完全溶解后方可加入?为什么不能往正在沸腾的溶液中加活性炭?
重结晶时,溶剂用量为什么不能过量太多,也不能太少?正确的用量应该是多少?