问题 问答题

①某病人因食盐摄入量不足,需要补充溶质质量分数约为0.9%的生理盐水,现医生确定每天为他注射200g生理盐水,则每天可为他补充约______g食盐.

②小明同学根据NaCl+AgNO3=AgCl↓(白)+NaNO3这一反应原理,对一瓶生理盐水进行分析时,不知道加入的硝酸银溶液与氯化钠溶液是否恰好完全反应,于是他设计了一个实验方案进行探究.请你帮他完善该实验方案.

探究步骤可能观察到的现象结论
①取反应后的上层清液于试管中,滴加______溶液若有白色沉淀生成______溶液过量
若无白色沉淀生成还需进行下一步探究
②另取反应后的上层清液于试管中,滴加______溶液

______

______溶液过量

______

______

答案

(1)根据溶质质量=溶液质量×溶质的质量分数=200g×0.9%=1.8g

故答案为1.8g.

(2)根据加入的氯化钠和硝酸银没有完全反应,可以分为氯化钠过量和硝酸银过量讨论,检验氯化钠用硝酸银,检验硝酸银用氯化钠.

 操作步骤 可能观察到的现象 结论
 (1)氯化钠溶液 若有白色沉淀生成 硝酸银溶液过量
 若无白色沉淀生成 
 (2)硝酸银溶液, 若有白色沉淀生成 氯化钠溶液过量
 若无白色沉淀生成 两者恰好完全反应

阅读理解

阅读理解

     Sadness is unpleasant, and in a society where personal happiness is prized above all else, there is little

tolerance for falling in despair.Especially now we've got drugs for getting rid of sad feelings-whether it's

after losing a job, the breakup of a relationship or the death of a loved one.So it's no surprise that more

and more people are taking them.

      But is this really such a good idea?A growing number of voices from the world of mental health

research are saying it isn't.They fear that the increasing tendency to treat normal sadness as a disease is

playing fast and loose (行为轻率). Sadness, they argue, serves a useful purpose-and if we lose it, we

lose out.Yet many psychiatrists (精神病医生) insist not.Sadness has a nasty habit of turning into

depression (抑郁症), they warn.Even when people are sad for good reason, they should take drugs to

make themselves feel better.

     So who is right?Is sadness something we cannot live without or something horrible never to touch?

There are lots of ideas about why feeling sad should become part of human life.It may be a selfprotection

strategy, as other primates (灵长类) also show signs of sadness.A losing monkey that doesn't show

sadness after it loses a fight may be seen as continuing to challenge the winning monkey-and that could

result in death.

     In humans, sadness has a further function:we may display sadness as a form of communication.By

acting sad, we tell other community members that we need support.

     Then there is the idea that creativity is connected to dark moods.There are plenty of great artists,

writers and musicians who have suffered from depression or disorder.Scientists find that people with

signs of depression perform better at a creative task, and that negative moods make people think deeply

over the unhappy experience, which allows creative processes to come to the front.There is also evidence

that too much happiness can be bad for your career.A doctor found that people who scored 8 out of 10

on a happiness test were more successful in income and education than 9s or 10s.The happiest people

lose their willingness to make changes to their lives that may benefit them.

1. The underlined word "this" refers to________.

A. taking drugs  

B. falling in despair

C. losing a job  

D. feeling sad

2. The author believes sadness is________.

A. a good thing for people's health

B. something horrible never to touch

C. a necessary function of humans

D. always to be treated as depression

3. Some animals show their sadness in order to________.

A. cheat their enemy 

B. protect themselves

C. comfort the loser  

D. challenge the winner

4. We can infer from the last paragraph that________.

A. people with great creativity tend to be happier

B. unhappy experiences contribute to a greater career

C. too much happiness can be bad for your career

D. the happiest people are the most successful ones

填空题