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| A．左侧高于右侧和右侧高于左侧 |
| B．右侧高于左侧和左侧高于右侧 |
| C．都为左右两侧一样高 |
| D．都为左侧高于右侧 |
实验步骤如下：①切取一小块金属钠，用滤纸完全吸干煤油，再除去表面的氧化层，放进干燥的E中；
②打开分液漏斗的活塞，使B中的反应进行一段时间后，再点燃E处的酒精灯。
实验现象如下：钠在充满C02气体的玻璃管中剧烈燃烧起来，产生大量的白烟；玻璃管中有黑色物质生成；待玻璃管冷却后，管壁上附着一层白色物质。
请回答下列问题：
（1）C中盛放的试剂是 ，作用是 。D中盛放的试剂是 ，作用是 。
（2）B中的反应进行一段时间后，再点燃E处的酒精灯的目的是 。
（3）该同学将白色物质和黑色物质分别溶于水，发现黑色物质不溶于水，白色物质能溶于水。由此，该同学得出结论，该黑色物质是Na与C02反应生成的碳单质，则其他生成物还应该有 。
（4）请设计一实验方案验证玻璃管内Na与C02反应生成的白色物质的成分，并写出实验步骤、现象和结论 。
（5）若先点燃E处的酒精灯，再打开分液漏斗的活塞，写出此时玻璃管E中可能发生的反应的化学方程式 。 查看习题详情和答案>>
Just a Quick Nap 只要打个盹儿
Do you feel a little sleepy after lunch? Well, that’s normal. Your body naturally slows down then. What should you do about it? Don’t reach for a coffee! Instead, take a nap.
It’s good to have a daily nap. First of all , you are more efficient（有效的） after napping . You remember things better and make fewer mistakes. Also, you can learn things more easily after taking a nap. A nap may increase your self-confidence（自信） and make you more active . It may even cheer you up. But, there are some simple rules you should follow about taking a nap. First, take a nap in the middle of day, about eight hours after you wake up. Next, a 20-minute nap is best. If you sleep longer, you may fall into a deep sleep. After waking from a deep sleep, you will feel worse. Also, you should set an alarm clock. That way, you can fully relax during your nap. You won’t have to keep looking at the clock so you don’t oversleep.
Now，the next time you feel sleepy after lunch , don’t get stressed . Put your head down, close your eyes, and catch forty winks.
【小题1】It is to get sleepy for you at noon.
A. normal B. strange C. amazing
【小题2】After taking a nap, you may feel more .
A. stressed B. confident C. sleepy
【小题3】The proper period（一段时间）of time for taking a nap is .
A. as long as you like B. eight hours C. about twenty minutes
【小题4】What can help you have a fully relaxing nap according to the passage?
A. A cup of coffee. B. A quick meal. C. An alarm clock.
【小题5】What is the text mainly about?
A. Why and how to take a nap.
B. Rules to increase your self –confidence.
C. How to make your body slow down.
Just a Quick Nap 只要打个盹儿
Do you feel a little sleepy after lunch? Well, that’s normal. Your body naturally slows down then. What should you do about it? Don’t reach for a coffee! Instead, take a nap.
It’s good to have a daily nap. First of all , you are more efficient（有效的） after napping . You remember things better and make fewer mistakes. Also, you can learn things more easily after taking a nap. A nap may increase your self-confidence（自信） and make you more active . It may even cheer you up. But, there are some simple rules you should follow about taking a nap. First, take a nap in the middle of day, about eight hours after you wake up. Next, a 20-minute nap is best. If you sleep longer, you may fall into a deep sleep. After waking from a deep sleep, you will feel worse. Also, you should set an alarm clock. That way, you can fully relax during your nap. You won’t have to keep looking at the clock so you don’t oversleep.
Now，the next time you feel sleepy after lunch , don’t get stressed . Put your head down, close your eyes, and catch forty winks.
1.It is to get sleepy for you at noon.
A. normal B. strange C. amazing
2.After taking a nap, you may feel more .
A. stressed B. confident C. sleepy
3.The proper period（一段时间）of time for taking a nap is .
A. as long as you like B. eight hours C. about twenty minutes
4.What can help you have a fully relaxing nap according to the passage?
A. A cup of coffee. B. A quick meal. C. An alarm clock.
5.What is the text mainly about?
A. Why and how to take a nap.
B. Rules to increase your self –confidence.
C. How to make your body slow down.
查看习题详情和答案>>