有一种工业废水,其中含有大量的硫酸镁,少量的银离子以及污泥.某同学设计了一个既经

题型:问答题

问题:

有一种工业废水,其中含有大量的硫酸镁,少量的银离子以及污泥.某同学设计了一个既经济又合

理的方法回收银和硫酸镁晶体.方案流程如下:

回答下列问题:

(1)步骤②中:需加入的物质是______.

(2)步骤③中:需加入的物质是______,当观察到______时,则停止加入该物质,发生反应的化学方程式是______.

(3)某同学认为经过步骤②后所得固体就是纯净的银,不需要进行步骤③,你认为是否合理?______,理由是______.

(4)步骤④的操作是______,溶液2和溶液3为什么要混合?______.

考点:蒸发蒸馏化学实验数据的分析置换反应化学反应方程式的书写
题型:问答题

阅读理解。

     New rules and behavior standards for middle school students came out in March. Middle school is

going to use a new way to decide who the top kids are. The best students won't have high marks. They

will also be kids who do not dye (染) their hair, smoke or drink. Here are some of the new rules.

     Tell the truth. Have you ever copied someone else's work on an exam? Don't do it again! That is not

something an honest student should do. If you've played computer games for two hours in your room,

do not tell your parents you have done homework.

     Do more at school. Good students always love animals and care for other people. April is Bird-loving

month in China. Are your schoolmates doing anything to celebrate? Join in it! In this way, you can learn

more about animals and how to protect them. When more people work together, it makes it more fun

for everyone. Have you ever quarreled with your teammates when your basket-ball team lost? Only

working together can make your team stronger. Be friendly to the people around you. Try to think of

others, not only yourself.

      Be open to new ideas. Have you ever thought that people could live on the moon? Maybe you'll

discover another Earth some day. Do not look down on new ideas. Everyone's ideas are important.

You should welcome them, because new ideas make life better for everyone.

      Protect yourself. Has someone ever taken money from one of your classmates? Don't let it happen

to you. If you have to go home late, you should take care of yourself and let your parents know.

      Use the Internet carefully. The Internet can be very useful for your studies. But some things on

the Internet aren't for kids, so try to look at Web pages that are good for you. You can use the Web

for fun or homework. Can't you find any good Web sites for children? Here are some: http:// kids.

east day.com; http:// www.chinakids.net.com.

1. The school new rules will help kids by telling them _____. [ ]

A. how they can study well  

B. what they should do only at school

C. what is right and what is wrong 

D. how they can protect themselves

2. According to the passage, which of the following is NOT true? [ ]

A. Take care of yourself when you are out.

B. Tell the truth, even when you are wrong.

C. Keep some animals to protect them.

D. Use the Internet, but keep away from bad things.

3. The main idea of the fourth paragraph is about _____. [ ]

A. making the team stronger     

B. working together each others

C. learning from each other     

D. being strict with others

4. Good Web sites for children can _____. [ ]

A. be a waste of time       

B. help them with their studies

C. do homework for them     

D. make their life easier

5. The passage tells us how to _____. [ ]

A. be top students      

B. do more at school

C. care for others    

D. use the Internet

题型:问答题

突然视力下降伴眼痛的眼病不包括()。

A.急性色素膜炎

B.视网膜脱离

C.急性闭角型青光眼

D.角膜炎

E.角膜水肿

题型:问答题

用来判断订单中的数量字段只包含数字的有效性检查属于以下()种控制。

A.输入控制 

B.审计轨迹控制 

C.处理控制 

D.数据安全控制

题型:问答题

破伤风抗毒素皮试结果阳性表现

A.亲密距离
B.个人距离
C.工作距离
D.公众距离
E.社会距离

题型:问答题

A survey done recently shows that not all parents __________ their children taking part in the

weekend classes.[ ]

A.escape  

B.lead to

C.imagine  

D.approve of

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