问题 选择题

向含有AgNO3、Cu(NO32的混合溶液中加入一定量的铁粉,充分反应后过滤,向滤出的固体中滴加稀硫酸,有气体生成,则滤出的固体一定为(  )

A.Ag、Cu两种单质的混合物

B.Cu、Fe两种单质的混合物

C.Ag、Fe两种单质的混合物

D.Ag、Cu、Fe三种单质的混合物

答案

向滤出的固体中滴加稀硫酸,有气泡产生,说明固体中含有铁,根据金属活动顺序知:Fe>Cu>Ag;所以AgNO3、Cu(NO32全部反应生成了单质铜和银.

故选D

阅读理解

阅读理解。

                                                                      Stop Spam

     When I first got an e-mail account ten years ago, I received communications only from family, friends,

and colleagues. Now it seems that every time I check my e-mail, I have an endless series of advertisements

and other correspondence that do not interest me at all. If we want e-mail to continue to be useful, we need

specific laws that make spamming (发送垃圾邮件) a crime.

     If lawmakers do not do something soon to prohibit spam, the problem will certainly get much worse.

Computer programs allow spammers to send hundreds of millions of e-mails almost instantly. As more and

more advertisers turn to spam to sell their products, individual (个人的) e-mail boxes are often flooded with

spam e-mails. Would people continue to use e-mail if they had to deal with an annoying amount of spam each

time?

     This problem is troubling for individuals and companies as well. Many spam e-mails contain computer

viruses that can shut down the entire network of a company. Companies rely on e-mail for their employees to

communicate with each other. Spam frequently causes failures in their local communications networks, and

their employees are thus unable to communicate effectively. Such a situation results in a loss of productivity

and requires companies to repeatedly repair their networks. These computer problems raise production costs

of companies, which are, in the end, passes on to the consumer.

     For these reasons, I believe that lawmakers need to legislate (立法) against spam. Spammers should be

fined, and perhaps sent to prison if they continue to disturb people. E-mail is a tool which helps people all over

the world to communicate conveniently, but spam is destroying this convenience.

1. What does the underlined word "correspondence" in the Paragraph 1 probably mean? 

A. messages

B. ideas

C. connections

D. programs

2. According to the text, what is the major cause of the flooding spam?

A. Companies rely on e-mail for communications.

B. More people in the world communicate by e-mail.

C. Many computer viruses contain spam e-mail.

D. More advertisers begin to promote sales through spam.

3. According to Paragraph 3, who is the final victim of spam?

A. The business

B. The advertiser

C. The employee

D. The consumer

4. What is the purpose of the text?

A. To inform

B. To educate

C. To persuade

D. To instruct

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