KMnO4滴定法，在酸性溶液中的反应常用H2SO4酸化，而不用HCl，为什么？

写出摩尔吸光系数的物理意义，摩尔吸光系数的大小与哪些因素有关写出常见有机化合物各种吸收带摩尔吸光系数的数值范围。

阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。

If you feel stressed by responsibilities at work, you should take a step back and identify (识别) those of   61  (great)and less importance. Then, handle the most important tasks first so you’ll feel a real sense of   62  (achieve). Leaving the less important things until tomorrow   63  (be) often acceptable.

Most of us are more focused   64   our tasks in the morning than we are later in the day. So, get an early start and try to be as productive   65   possible before lunch. This will give you the confidence you need to get you through the afternoon and go home feeling accomplished.

Recent   66  (study) show that we are far more productive at work if we take short breaks   67  (regular). Give your body and brain a rest by stepping outside for   68   while, exercising, or dong something you enjoy.

If you find something you love doing outside of the office, you’ll be less likely   69  (bring) your work home. It could be anything-gardening, cooking, music, sports—but whatever it is,   70  (make) sure it’s a relief from daily stress rather than another thing to worry about.

68（）

若有以下程序：
#include 〈iostream〉
using namespace std;
class sample

private:
int i;
public:
void setvalue(int m)

i=m;

void fun(int m)

i+=m;

void disp()

cout〈〈i〈〈end1;

;
int main()

sample *ps;
ps=new sample;
ps->setvalue(20);
ps->fun(5);
ps->disp();
return 0;

程序运行后，输出的结果是( )。

A．15

B．20

C．25

D．30

巴黎圣母院西立面是典型的哥特式（）构图

锅炉本体的主要受压部件有（）、烟管、火管、过热器、再热器和省煤器等。