问题 填空题

现有(1)氧气(2)食盐水(3)氯化镁(4)空气(5)水银(6)氧化铁(7)水(8)高锰酸钾等物质,其中属于混合物的是____________,属于单质的是_____________;属于化合物的是____________;属于氧化物的是_______________。(填序号)

答案

(2)(4);(1)(5);(3)(6)(7)(8);(6)(7)

单项选择题
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     I'm usually fairly skeptical about any research that concludes that people are either happier or

unhappier or more or less certain of themselves than they were 50 years ago. While any of these

statements might be true, they are practically impossible to prove scientifically. Still, I was struck by

a report which concluded that today's children are significantly more anxious than children in the

1950s. In fact, the analysis showed, normal children aged 9 to 17 exhibit a higher level of anxiety today

than children who were treated for mental illness 50 years ago.

     Why are America's kids so stressed? The report cites two main causes: increasing physical isolation

(隔离) brought on by high divorce rates and less involvement in community, among other things and a

growing perception that the world is a more dangerous place.

     Considering that we_can't_turn_the_clock_back,_adults can still do plenty to help the next

generation.

     At the top of the list is nurturing(培育) a better appreciation of the limits of individualism. No child is

an island.  Strengthening social ties helps build communities and protect individuals against stress.

     To help kids build stronger connections with others, you can pull the plug on TVs and computers. 

Your family will thank you later. They will have more time for facetoface relationships, and they will get

more sleep.

     Limit the amount of virtual(虚拟的) violence your children are exposed to. It's not just video games

and movies; children see a lot of murder and crime on the local news.

Keep your expectations for your children reasonable. Many highly successful people never attended

Harvard or Yale.

     Make exercise part of your daily routine. It will help you cope with your own anxieties and provide

a good model for your kids. Sometimes anxiety is unavoidable. But it doesn't have to ruin your life.

1. According to the analysis, compared with normal children today, children treated as mentally ill 50 years ago ________.

A. probably suffered less from anxiety

B. were considered less individualistic

C. were less isolated physically

D. were probably less selfcentered

2. What does the author mean by saying "we can't turn the clock back" in the third paragraph?

A. It's impossible to forget the past.  

B. The social reality children are facing cannot be forgotten.

C. It's impossible to slow down the pace of change.

D. Lessons learned from the past should not be forgotten.

3. The author thinks that the conclusions of any research about people's state of mind are ________.

A. illogical  

B. confusing

C. surprising  

D. questionable