The newly-found slimming drug can successfully suppress appetite because __

Leptin __________. 查看材料

A.refers to a new biochemical pathway in the brain that controls appetite

B.raises new prospects for developing slimming drugs

C.is a hormone produced in fatty tissue for controlling fat build-up

D.has turned to a breakthrough in the search for effective slimming drug

ffective in mice， is likely to work on humans because __________. 查看材料

A.the chemical pathway responsible for appetite control in human is believed to be the same as that in mice

B.it is a major pathway in the brain which is activated to regulate appetite

C.it is especially effective in the battle against obesity

D.its effect has also been proved by human studies

根据以下材料，回答题

A New Drug for Losing Weight

Scientists have developed a slimming drug that successfully suppresses appetite and results in a dramatic loss of weight without any apparent ill effects. The drug interferes with appetite control and prevents the build-up of fatty tissue. More importantly， the drug appears to prevent a serious decline metabolic rate——causing tiredness and lethargy——which is typically associated with living on a starvation diet. S a result， mice taking the drug lost 45 percent more weight than mice fed the same amount of food， which compensate for the lack of food by becoming more sluggish.

The scientists， from the Johns Hopkins University in Baltimore， said that C75 is likely to produce a similar effect on humans because appetite control in the brain is thought to be based largely on the same chemical pathways as those in mice. "We are not claiming to have found the fabled weight-loss drug. What we have found， using C75， is a major path way in the brain that the body uses naturally in regulating appetite at least in mice，" said Francis Kuhajda， a pathologist and senior team member. "We badly need effective drugs for weight loss. Obesity is a huge problem.

We"re hoping to explore the possibilities of this new pathway，" he said.

Discovering a biochemical. Pathway in the brain that controls appetite raises new prospects for eloping slimming aids. Research on leptin， a hormone produced in fatty tissue for controlling fat deposits， has so far failed to produce the expected slimming drug break-through. The latest study， published in the journal Science， showed that even moderate doses of C75 produced a significant loss of appetite， which returned to normal after a few months.

The scientists believe that C75， which they produced synthetically in the laboratory， binds to an enzyme called fatty acid sythase， which is involved in storing excess food intake as fat.

Inhibiting enzyme causes a build-up of a chemical in the liver which acts as a precursor to fat deposition. This precursor is thought to have an indirect effect on the brain， causing appetite suppression.

Normally， when animals fast， a hormone called neuropeptide Y increases sharply in the appe-tite control centers of the brain， stimulating the desire for food. However， when animals are given C75， levels of this hormone fall， leading to a loss of interest in food. Dr Kuhajda said discovering that C75 has no effect on metabolic rate is one of the most significant findings of the study. "If you try to lose weight by starving， your metabolism slows down after a few days，" he said. "It"s a survival mechanism that sabotages many diets. We see this in fasting mice. Yet metabolic rate in the C75-treated mice doesn"t slow at all. "Further animals studies will be needed before C75 could be tested on humans.

Living on a starvation diet may result in __________. 查看材料

A.a dramatic loss of weight without any ill effects

B.a long-term loss of interest in eating

C.a slowdown of fat deposition

D.fatigue and inactivity

根据以下材料，回答题

The Doctor in America

Self-employed private physicians who charge a fee for each patient visit have been the norm for American medical practice. Most physicians have a contract relationship with one or more hospitals in their community. They refer their patients as needed to the hospital， which usually charges according to the number of days a patient stays and the facilities —— X-rays，operating rooms， tests —— he or she uses.

Some medical doctors are on salary. Salaried physicians may work as hospital staff members， or residents， who are often still in training. They may teach in medical schools， be hired by corporations to care for their workers or work for the federal government"s Public Health Service.

Physicians are among the best-paid professionals in the United States. In the 1980s， it was not uncommon for medical doctors to， earn incomes of more than $100，000 a year. Specialists，particularly surgeons， might earn several times that amount. Physicians list many reasons why they deserve to be so well rewarded for their work. One reason is the long and expensive preparation required to become a physician in the United States. Most would-be physicians first attend college for four years， which can cost nearly $20，000 a year at one of the best private institutions. Prospective physicians then attend medical school for four years. Tuition alone can exceed $10，000 a year. By the time they have obtained their medical degrees， many young physicians are deeply in debt. They still face three to five years of residency （住院医生实习期） in a hospital， the first year as an apprentice physician. The hours are long and the pay is relatively low.

Setting up a medical practice is expensive， too. Sometimes several physicians will decide to establish a group practice， so they can share the expense of maintaining an office and buying equipment. These physicians also take care of each other"s patients in emergencies.

Physicians work long hours and must accept a great deal of responsibility. Many medical procedures， even quite routine ones， involve risk. It is understandable that physicians want to be well rewarded for making decisions which can mean the difference between life and death.

Many physicians in the US are self-employed private physicians. 查看材料

A.Right

B.Wrong

C.Not mentioned

I rarely visit my parents after I obtained a job in this company.

A.seldom

B.frequently

C.normally

D.eventually

The dentist has decided to extract her bad tooth.

A.take out

B.take in

C.turn out

D.turn in

It seemed inevitable for him to make such mistake because of his carelessness.

A.strange

B.certain

C.consistent

D.unavoidable

It was his finn conviction that every effort should be made to preserve world peace.

A.doubt

B.belief

C.persuasion

D.enthusiasm

Many fine cooks insist on ingredients of the highest quality.

A.structure

B.materials

C.sections

D.branches

It is difficult to make a film meeting the various needs of all our users.

A.diverse

B.similar

C.versatile

D.distinguished