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Millions of people are using cell phones today. In many places it is actually considered unusual not to use one. In many countries, cell phones are very popular with young people. They find that the phones are more than a means of communication-having a mobile phone shows that they are cool and connected.
The explosions around the world in mobile phone use make some health professional worried. Some doctors are concerned that in the future many people may suffer health problems from the use of mobile phones. In England, there has been a serious debate about this issue. Mobile phone companies are worried about the negative publicity of such ideas. They say that there is no proof that mobile phones are bad for your health.
On the other hand, why do some medical studies show changes in the brain cells of some people who use mobile phones? Signs of change in the issues of the brain and head can be detected with modern scanning (扫描) equipment. In one case, a traveling salesman had to retire at a young age because of serious memory loss. He couldn't remember even simple tasks. He would often forget the name of his own son. This man used to talk on his mobile phone for about six hours a day, every day of his working week, for a couple of years. His family doctor blamed his mobile phone use, but his employer's doctor didn't agree.
What is it that makes mobile phones potentially harmful? The answer is radiation. High-tech machines can detect very small amounts of radiation from mobile phones. Mobile phone companies agree that there is some radiation, but they say the amount is too small to worry about.
As the discussion about their safety continues, it appears that it's best to use mobile phones less often. Use your regular phone if you want to talk for a long time. Use your mobile phone only when you really need it. Mobile phones can be very useful and convenient, especially in emergencies. In the future, mobile phones may have a warning label that says they are bad for your health. So for now, it's wise not to use your mobile phone too often
31 People buy cell phones for the following reasons EXCEPT that
A they're popular
B they're useful
C they're convenient
D they're cheap
32 The world "detected" in paragraph 3 could be best replaced by
A cured
B removed
C discovered
D caused
33 The salesman retired young because
A he couldn't remember simple tasks
B he disliked using mobile phones
C he was tired of talking on his mobile phone
D his employer's doctor persuaded him to
34. On the safety issue of mobile phones, the manufacturing companies
A hold that the amount of radiation is too small to worry about
B deny the existence of mobile phone radiation
C develop new technology to reduce mobile phone radiation
D try to prove that mobile phones are not harmful to health
35 The writer's purpose of writing this article is to advise people
A to buy mobile phones
B to use mobile phones less often
C to update regular phones
D to stop using mobile phones
第二篇 Immune Functions
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communication network consulting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees flying around a hive(蜂巢). The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-omitting.
At the heart of the immune system is the ability to distinguish between self and nonself. When immune defenders encounter cells or organisms carrying foreign of nonself molecules, the immune troops move quickly to eliminate the intruders (入侵者). Virtually every body cell carries distinctive molecules that identify it as self. The body's immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a nonself molecule, the system has the ability to "remember" the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies(抗体)passed during lactation(授乳期), this so called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must "learn" from experience with the many millions of distinctive nonself molecules in the sea of microbes (微生物) in which we live, learning necessitates producing the appropriate molecules and cells to match up with and counteract each nonself invader.
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