【推荐1】If there is no difference in general intelligence between boys and girls, what can explain girls’ poor performance in science and mathematics?

It seems to be that their treatment at school is a direct cause. Mathematics and science are seen as subjects mainly for boys, and therefore, as girls become teenagers, they are less likely to take them. Interestingly, both boys and girls often regard the subjects for boys as more difficult. Yet it has been suggested that girls do not take mathematics courses, not because they are difficult, but for social reasons. Girls do not want to be in open competition with boys because they are afraid to appear less feminine and attractive.

However, if we examine the performance of boys and girls who have taken mathematics courses, there are still more high-achieving boys than there are girls. This difference appears to be world-wide. Biological explanations have been offered for this, but there are other explanations too.

Perhaps the difference which comes out during the teenage years has its roots in much earlier experiences. From their first days in kindergarten, boys are encouraged to work on their own and to complete tasks. Facts show that outstanding mathematicians and scientists have not had teachers who supplied answers.

Besides, there can be little doubt that teachers of mathematics and science expect their boy students to do better at these subjects than their girl students. They even appear to encourage the difference between boys and girls. They spend more time with the boy students, giving them more time to answer questions and working harder to get correct answers from them. They are more likely to call on boys for answers and to allow them to take the lead in classroom discussion. They also praise boys more frequently. All of this seems to encourage boys to work harder in science and mathematics and to give them confidence that they are able to succeed.

Such a way of teaching is not likely to encourage girls to take many mathematics and science courses, nor is it likely to support girls who do. When it comes to these subjects, it seems certain that school widens the difference between boys and girls.

1. Girls are likely to think that _________.

A．science courses are for both boys and girls	B．science courses make them more popular
C．science courses make them successful	D．science courses are difficult for them

2. What does the underlined word “feminine” in para.2 probably mean?

A．Polite.

B．Female

C．Determined

D．Competitive

3. What does the passage say about great mathematicians?

A．Their teachers did not supply answers to them.

B．They started learning mathematics at an earlier age.

C．They showed mathematical abilities in their teenage years.

D．Their success resulted from their strong interest in mathematics.

4. The author would probably agree that _________.

A．boys and girls learn in the same way

B．boys and girls are equal in general intelligence

C．girls are more confident in themselves than before

D．girls should take fewer science courses than boys

【推荐2】If you think you’ve gained too much weight or are too skinny, you can talk to a doctor. Your doctor will tell you     1    .

If it is concerned about your height, weight, or BMI (体重指数), your doctor may ask questions    2    . Your doctor may also ask about your family background to find out if you’ve received something from your parents that might make you taller, shorter, or a late bloomer(someone who develops later than other people of the same age). The doctor can then put all the information together to decide     3    .

If your weight isn’t in a healthy range, you will probably get specific diet and exercise recommendations (推荐) based on our individual needs. Following a doctor’s or dietitian’s plan designed especially for you will work much better than following fad (时尚) diets. For teens, fad diets or starvation plans can actually slow down growth, and the weight loss usually doesn’t last.

What     4    ? Most teens who weigh less than other teens of their age are just fine. They may be going through puberty on a different schedule than kids of the same age, and their bodies may be growing and changing at a different rate. Most underweight teens catch up in weight as they finish puberty during their later teen years so there’s rarely a need to try to gain weight.

In a few cases, teenagers can be underweight because of a health problem that needs treatment. If you feel tired or ill a lot, or     5    , or other problems that have lasted for more than a week or two, be sure to let your parents or your doctor know.

A．whether you might have a weight or growth problem

B．if you have symptoms (症状) like a cough, stomachache

C．about your health, physical activity, and eating habits

D．if you’re worried about being too skinny

E．if you take care of it

F．whether you’re growing normally

G．about your dieting

【推荐3】Humans work hard to avoid viruses. Sick people are isolated, diseased animals are killed and fields of infected crops are fired up. Reviving (复活) an ancient virus would surely be a disaster.

But a new study led by Fiddamanfrom Oxford, challenges this conventional wisdom. It shows how the revival of an ancient virus can unlock the secrets of its evolution.

The virus in the study is Marek’s disease virus(MDV), killing more than 90% of chickens. Yet when it was discovered in 1907, MDV rarely caused death.

Dr Fiddaman wondered whether its new-found virulence (毒性) was a result of large structural changes. To find out, he and his colleagues got their hands on nearly 1,000 chicken bones from ancient times across Europe and Asia, some of them up to 2000 years old. Sections of DNA from these remains were mapped onto the ones of today’s virus.

As the authors pieced together the sets of genes of ancient MDV, however, they noticed that the genes were arranged identically to those in modern species. It suggests that the increased virulence resulted not from large structural changes, but from point mutations (突变). In particular, changes had occurred in the arrangement of a gene called MEQ, which has an essential role in tumour (肿瘤) formation.

This discovery suggests that the ancient MDV may not have been able to cause tumours. To test this assumption, Dr Fiddaman followed up with a daring experiment. He made the ancient form of the MEQ gene and shoot it into living chicken cells. It did not turn on any of the genes associated with tumour formation. In comparison, a modern MEQ gene quickly showed its tendency to cause tumours.

By combining ancient and modern genetic biology, the methods pioneered in the paper reveal how, and more importantly why, any virus mutates. That could help scientists tackle other viruses that pull on the purse-strings of farmers—by designing new vaccines (疫苗), for instance—or even to work out how to prevent another global pandemic.

1. What does the underlined phrase “were mapped onto” mean in paragraph 4?

A．were restricted to	B．were opposed to
C．were compared with	D．were filled with

2. What caused the virulence change of MDV?

A．Point mutations in MEQ.	B．The occurrence of a new gene.
C．The reproduction of the ancient MDV.	D．Large structural changes in modern species.

3. How did Dr Fiddaman test the assumption?

A．By investigating a typical case.	B．By conducting a field survey.
C．By studying the related theories .	D．By doing a comparative experiment.

4. What can we infer from the last paragraph?

A．Viruses weaken gradually when they mutate.

B．The finding throws light on handling other viruses.

C．A global pandemic requires a world effort to end it.

D．Farmers will face more complex challenges than before.