_______isit? It'sblue.[ ] A.Whatcolour B

饮水安全是人们关注的重要问题，特别是在严重灾害的时期．请你运用以下资料及所学的化学知识，为灾害时期解决安全饮水的问题．

【资料在线】我国生活饮用水的标准

感官指标	化学指标	细菌学指标
水质无色无味且澄清透明	pH：6.5-8.5；总硬度＜250mg/L（以碳酸钙计）；铜＜1.0mg/L…等	细菌总数＜100个/mL等

（1）①测定水样的pH可选用______．

②检验水样是硬水还是软水，通常可向其中加入______．

（2）符合感官和化学指标的水还不一定是安全的饮用水，理由是______．

Questions 21-25 are based on the following passage:

I hear many parents complaining that their teenage children are rebelling. I wish it were so. At your age you ought to be growing away from your parents. You should be learning to stand on your own two feet. But take a good look at the present rebellion. It seems that teenagers are all taking the same way of showing that they disagree with their parents. Instead of striking out boldly on their own, most of them are clutching at one another’s hands for courage. They claim they want to dress as they please. But they all wear the same clothes. They set off in new directions in music. But somehow they all end up just by listening to the same record. Their reason for thinking or acting in this way is that the crowd is doing it. It has become harder and harder for a teenager to stand up against the popularity wave and to go his or her own way. Industry has firmly carved out a teenage market. These days every teenager can learn from the advertisements what a teenager should have and be. And many of today’s parents have come to award high marks for the popularity of their children. All this adds up to a greater barrier for the teenager who wants to find his or her own path. But the barrier is worth climbing over. The path is worth following. Find yourself. Be yourself. Popularity will come--with the people who respect you for whom you are. That’s the only kind of popularity that really counts.

The author thinks of advertisements as ______.

A．original

B．influential

C．detrimental

D．authoritative

患者，经产妇，34岁，孕35周，全身皮肤黄疸半个月，血压120/90mmHg，既往妊娠也有同样病史，产后黄疸可自行消退。肝功能：谷丙转氨酶150U/L。若考虑为妊娠期肝内胆汁淤积症，应首选下列哪项检查（）

A.胆固醇

B.胆汁酸

C.血清总胆红素

D.麝香草酚浊度试验

E.尿胆红素

下列工资收入属于国民收入初次分配的是( )。

A．国家机关工作人员的工资

B．工业企业职工的工资

C．高等学校教师的工资

D．文艺工作者的工资

第几届奥运会开始发行奥林匹克邮票？（）