Spending a lot of time watching TV, playing video games and surfing the Web causes a lot of healthy problems to children such as overweight and smoking, US researchers said yesterday.

U.S. experts analyzed 173 studies on how media sources influence the physical health of children and adolescents (青少年). The studies, mostly carried out in the United States, largely focused on television, but some looked at video games, films, music, computer and Internet use. Three quarters of them found that increased media viewing was connected with poor health.

The studies offered strong evidence that children who get more media exposure are more likely to become overweight, start smoking and begin earlier sexual activity than those who spend less time in front of a screen, the researchers said. Studies also showed more media exposure is linked to drug and alcohol use and poorer school performance. “We were pretty surprised by the number of studies that showed these negative health results,” said one of the researchers in the report.

For decades, experts have worried about the effect on young viewers of the violence and sexual content in some TV programs, movies and video games. Another issue is that kids are spending time sitting on a couch（長(zhǎng)沙發(fā)) watching TV or playing computer games when they could be running around outside.

One study found that children who spend more than eight hours watching TV per week at age 3 are more likely to be overweight at 7. And research showed that many US children watch far more. Another study showed TV and other media content can have a deep influence on children’s attitudes and beliefs, particularly among teens. A US study published in November showed that adolescents who watched more programs with sexual themes had a higher risk of becoming pregnant (懷孕的) or causing a pregnancy. Thirteen of 14 studies that evaluated (評(píng)估）sexual behavior found a connection between media exposure and earlier sexual behavior, the researchers said.

57. How did the experts carry out their research?

A. By examining health problems including overweight and smoking.

B. By analyzing 173 studies on influences of media sources.

C. By watching TV, playing video games and surfing the Web.

D. By offering strong evidence that children become overweight.

58. According to the passage, too much media exposure may cause the following EXCEPT _______.

A. drug and alcohol use                                    B. overweight, smoking, sexual problem

C. progress in school subjects                           D. poor health results and violence

59. By mentioning adolescent pregnancy, the author tries to tell us that _______.

A. we’d better get rid of TV, movies, and the Internet

B. the present generation of youths is hopeless

C. sexual themes are as bad as violent themes

D. some media contents have a bad effect on teens

60. What’s the best title for this passage?

A. What’s the Cause of Children’s Overweight?    

B. Violence and Sexual content in TV programs.

C. Lots of TV, Video, Web Harms Kids’ Health.

D. Media Exposure and Adolescent Pregnancy.

Age plays a major part in people who are infected with cold, ie, in people who suffer from cold infection. A study done by University of Michigan, has shown information that seems to be true for the general population. Babies are the most cold infected group, generally more than six colds in their first years. Boys have more colds than girls up to the age of three. After three, girls are easier to get infected with cold than boys, and teenage girls get three colds a year to boys’ two. The general cold infections continue to get less into adults. Elderly people who are in good health have as few as one or two cold every year. One interesting thing is found among people in their twenties, especially women, who show a rise in cold infection, because people in this age are most likely to have young children.

The study has also found that economy plays an important role as well. With more and more income, the frequency at which colds are reported in the family is getting lower and lower. Families with the lowest income usually suffer about a third more colds than families at the upper end. Lower income usually forces people to live in rooms more crowded than rooms owned by richer people, and the crowding usually leads to more chances for the cold virus to travel from person to person. Low income may also have an effect on our diet. Many scientists believe that a poorer diet usually leads into more possibilities of cold infection.

1．Which of the age groups has the highest frequency of cold infection?

       A．Small babies      B．Teenage boys     C．Adult women     D．Elderly people

2．The purpose of writing this passage is to _________.

A．give the readers some tips to avoid cold infection

      B．show a carefully-made study on cold infection

C．report the major reasons leading to cold infection

D．describe all the possible dangers of cold infection

3．How does economy play an important role in cold infection?

A．Families with lower income suffer less from cold infection

B．People who have lower income enjoy living in crowded rooms

C．Rich families can have better nutrition and never get infected

D．People with higher income have fewer chances of infection

4．From the passage we can infer that ___________.

A．a(chǎn)ge is the only important factor that connects with colds

B．families with the highest income will more easily get infected

C．people have lower frequency of infection as they grow older

D．a(chǎn) better diet may help people to fight against cold infection

When nature is left alone, a balance is reached among the animals and plants living in one area. But when man starts his work in nature, the balance is likely to be destroyed. He grows a crop and takes it away to eat; then there are no dead leaves to fall on the ground, holding water while it sinks into the surface, or decaying (腐爛) and adding humus (腐殖質(zhì)) to the soil. Unless a farmer acts with knowledge and skill, he is therefore most likely to make the land poorer. To take the place of the useful matter in the crops that he removes, he uses some kind of fertilizer. Chemical fertilizers are of great help, but the waste products of animals and decaying remains of plants should also be put on the land. In some places, it is a habit to burn waste material lying about, but such burning destroys the useful matter in the dead plants. Although the ashes that are left are valuable when put on the land, a better practice is to bury the waste so that it decays and increases the humus in the soil.

In the past, when the world population was much lower than it is now, a man had little difficulty in ordinary times in growing the food that was needed. When a field had been used some years and had become tired, the farmer could move to another place. The tired land then slowly recovered. Gradually grasses and other plants would appear on it and its productive power would slowly return to normal through their decay. But nature, left alone, would take a long time to bring back the land to its former state; the length of time required would depend on local conditions, but it might well be ten years.

It is a bad practice to grow the same crop in a field year after year. If the crop is changed, the land will suffer less because it is treated and used in a different way. Different plants have different effects on the soil. Therefore, a change of crop will do less harm than the growing of the same crop year after year and a regular change to grass will do good to the soil. Much will therefore be gained if different crops are grown one after another, a method known as the rotation (輪作) of crops.

According to the passage, the land will become poorer________.

A. if all the dead leaves are cleared away        

B. if the humus is increased after the harvest

C. if dead leaves decay in the soil by themselves 

D. if waste plant material lying about is buried

We can learn from the passage that the tired land has gradually recovered_______.

A. when grasses and other plants appear again

B. when the treatment is given by nature alone

C. after new grasses and other plants have decayed again

D. after nature has been left alone for several months

A modern farmer can hardly move to another place as he did before because_______.

A. the productive power of a new field isn't higher than that of an old one

B. there are few free fields left for him to do farming

C. it takes a farmer more than ten years to start farming in a new field

D. there will be too many grasses in a new field to grow crops

It is most likely that the author will go on to ______ in the paragraph following the passage above.

A. introduce other methods of planting crops     

B. deal with how to prevent land getting tired

C. start another topic of how to make use of land

D. explain what the rotation of crops is      

When nature is left alone, a balance is reached among the animals and plants living in one area. But when man starts his work in nature, the balance is likely to be destroyed. He grows a crop and takes it away to eat ;then there are no dead leaves to fall on the ground, holding water while it sinks into the surface, or decaying (腐爛) and adding humus (腐殖質(zhì)) to the soil. Unless a farmer acts with knowledge and skill, he is therefore most likely to make the land poorer. To take the place of the useful matter in the crops that he removes, he uses some kind of fertilizer (肥料). Chemical fertilizers are of great help, but the waste products of animals and decaying remains of plants should also be put on the land. In some places, it is a habit to burn waste material lying about, but such burning destroys the useful matter in the dead plants. Although the ashes that are left are valuable when put on the land, a better practice is to bury the waste so that it decays and increases the humus in the soil.

In the past, when the world population was much lower than it is now, a man had little difficulty in ordinary times in growing the food that was needed. When a field had been used some years and had become tired, the farmer could move to another place. The tired land then slowly recovered. By and by grasses and other plants would appear on it and its productive power would slowly return to normal through their decay. But nature, left alone, would take a long time to bring back the land to its former state; the length of time required would depend on local conditions, but it might well be ten years.

It is a bad practice to grow the same crop in a field year after year. If the crop is changed, the land will suffer less because it is treated and used in a different way. Different plants have different effects on the soil. Therefore, a change of crop will do less harm than the growing of the same crop year after year and a regular change to grass will do good to the soil. Much will therefore be gained if different crops are grown one after another, a method known as the rotation (輪作) of crops.

According to the passage, the land will become poorer (   )

A. if all the dead leaves are cleared away        B. if the humus is increased after the harvest

C. if dead leaves decay in the soil by themselves  D. if waste plant material lying about is buried

We can learn from the passage that the tired land has slowly recovered (   )

A. when grasses and other plants appear again

B. when the treatment is given by nature alone

C. after new grasses and other plants have decayed again

D. after nature has been left alone for several months

A modern farmer can hardly move to another place as he did before because (   )

A. the productive power of a new field isn't higher than that of an old one

B. there are few free fields left for him to do farming

C. it takes a farmer more than ten years to start farming in a new field

D. there will be too many grasses in a new field to grow crops

It is most likely that the author will go on to (   ) in the paragraph following the passage above.

A. introduce other methods of planting crops     B. deal with how to prevent land getting tired

C. start another topic of how to make use of land  D. further explain what the rotation of crops is