The Best Way to Reduce Your Weight
You hear this:"No wonder you are fat. All you ever do is eat. " You feel sad:"l skip my breakfast and supper. I run every morning and evening. What else can I do?" Basically you can do nothing. Your genes, not your life habits, determine your weight and your body constantly tries to maintain it.
Albert Stunkard of the University of Pennsylvania found from experiments that, "80 percent of the children of two obese (肥胖的) parents become obese,as compared with no more than 14 percent of the offspring of two parents of normal weight. "
How can obese people become normal or even thin through dieting? Well,dieting can be effective, but the health costs are tremendous. Jules Hirsch, a research physician at Rockefeller University, did a study of eight fat people. They were given a liquid formula providing 600 calories a day.After more than 10 weeks,the subjects lost 45ka on average. But after leaving the hospital,they all regained weight. The results were surprising: by metabolic (新陈代谢的) measurement, fat people who lost large amounts of weight seemed like they were starving. They had psychiatric problems. They dreamed of food or breaking their diet. They were anxious and depressed; some were suicidal. They hid food in their rooms. Researchers wam that it is possible that weight reduction doesn't result In normal weight,but in an abnormal state resembling that of starved non - obese people.
Thin people, however, suffer from the opposite: They have to make a great effort to gain weight. Ethan Sims, of the University of Vermont, got prisoners to volunteer to gain weight. In four to six months,they ate as much as they could. They succeeded in increasing their weight by 20 t0 25 percent. But months after the study ended they were back to normal weight and stayed there.
This did not mean that people are completely without "hope in controlling their weight. It means that those who tend to be fat will have to constantly battle their genetic inheritance if they want to significantly lower their weight. The findings also provide evidence for something scientists thought was true - each person has a comfortable weight range. The range might be as much as 9kg. Someone might weigh 60-69kg without too much effort. But going above or below the natural weight range is difficult. The body resists by feeling hungry or full and changing the metabolism to pusb the weight back to the range it seeks.
31. What determines your weight?
A. Your working manner.
B. Your eating habit.
C. Your life style.
D. Your genes.
32. What did Jules Hirsch do in his study?
A. He let the eight fat people skip supper.
B. He let the eight fat people skip breakfast.
C. He let the eight fat people run every morning and evening.
D. He gave the eight fat people a liquid formula providing 600 calories a day.
33. What happened to the eight fat people after they left the hospital?
A. They went mad.
B. They killed themselves.
C. They were back to normal weight.
D. They attempted suicide
34. What did Ethan Sims make his subjects do?
A. Battle their genetic inheritance.
B. Increase their weight.
C. Stay at home.
D. Lower their weight.
35. What did scientists think was true?
A. Each person has a fixed weight range.
B. Each person has a weight range of 9 kg.
C. Each person wants to control his weight.
D. Each person wants to eat to his heart's content.
Black Holes Trigger stars self-destruction
Scientists have long understood that supermassive black holes weighing millions or billions of suns can tear apart stars that come too close.The black hotels gravity pulls harder on the nearest part of the star，an imbalance that pulls the star apart over a period of minutes or hours，once it gets close enough.
Scientists say this Uneven pulling is not the only hazard facing the star.The strain of these unbalanced forces can also trigger a nuclear explosion powerful enough to destroy the star from within.Matthieu Brassart and Jean-Pierre Luminet of the Observatoire de Paris in Meudon，France1，carried out computer simulations of the final moments of such an unfortunate star‘s life，as it veered towards a supermassive black hole.
When the star gets close enough，the uneven forces flatten it into a pancake shape.Some previous studies had suggested this flattening would increase the density and temperature inside the star enough to trigger intense nuclear reactions that would tear it apart.But other studies had suggested that the picture would be complicated by shock waves generated during the flattening process and that no nuclear explosion should occur.
The new simulations investigated the effects of shock waves in detail，and found that even when their effects are included，the conditions favor a nuclear explosion.“There will be an explosion of the star — it will be completely destroyed，” Brassart says. Although the explosion obliterates the star，it saves some of the star‘s matter from being devoured by the black hole.The explosion is powerful enough to hurl much of the star’s matter out of the black hole‘s reach，he says.
The devouring of stars by black holes may already have been observed，although at a much later stage.It is thought that several months after the event that rips the star apart，its matter starts swirling into the hole itself.It heats up as it does so，releasing ultraviolet light and X-rays.
If stars disrupted near black holes really do explode，then they could in principle allow these events to be detected at a much earlier stage，says Jules Hatpern of Columbia University in New York，US2.“It may make it possible to see the disruption of that star immediately if it gets hot enough，”
Brassart agrees.“Perhaps it can be observed in the X-rays and gamma rays，but it‘s something that needs to be more studied，” he says.Supernova researcher Chris Fryer of the Los Alamos National Laboratory in Los Alamos，New Mexico，US3，says the deaths of these stars are difficult to simulate，and he is not sure whether the researchers have proven their case that they explode in the process.
36. Something destructive could happen to a star that gets too close to a black hole. Which of the following statements is NOT mentioned in the passage?
A. The black hole could tear apart the star.
B. The black hole could trigger a nuclear explosion in the star.
C. The black hole could dwindle its size considerably.
D. The black hole could devour the star.
37. According to the third paragraph, researchers differed from each other in the problem of
A. whether nuclear reaction would occur.
B. whether the stars would increase its density and temperature.
C. whether shock waves would occur.
D. whether the uneven forces would flatten the stars.
38. According to the fourth paragraph, which of the following is NOT true?
A. No nuclear explosion would be triggered inside the star.
B. The star would be destroyed completely.
C. Much of the star's matter thrown by the explosion would be beyond the black hole's reach.
D. The black hole would completely devour the star.
39. What will happen several months after the explosion of the star?
A. The star's matter will move further away from by the black hole.
B. The black hole's matter will heat up.
C. The black hole's matter will swirl into the black hole.
D. The black hole's matter will release ultraviolet light and X-rays.
40. According to the context, the word "disruption" in paragraph 6 means
A. confusion.
B. tearing apart.
C. interruption.
D. flattening.
Where Have Allthe Bees Gone?
Scientists who study insects have a real mystery on theirhands.All across the country，honeybees are leaving their hives and neverreturning. Researchers call this phenomenon colony-collapse1 disorder.Accordingto surveys of beekeepers across the country，25 to 40 percent of the honeybeesin the United States have vanished from their hives since last fall.So far，noone can explain why.
Colony collapse is a serious concern because bees playan important role in the production of about one-third of the foods we eat.Asthey feed，honeybees spread pollen from flower to flower.Without this process，aplant can’t produce seedsor fruits.
Now，a group of scientists andbeekeepers have teamed up to try to figure out what’s causing the alarmingcollapse of so many colonies. By sharing their expertise in honeybee behavior，health，and nutrition，team members hope to find out what’s contributingto thedecline and to prevent bee disappearance in the future.
Itcould be that disease is causing the disappearance of the bees. To explore that possibility，Jay Evans，a researcher at the United States Department ofAgriculture (USDA) Bee Research Laboratory2，examines bees taken from coloniesthat are collapsing.“We know what a healthy bee should look like on theinside，and we can look for physical signs of disease,” he says. And bees fromcollapsing colonies don’t look very healthy. “Their stomachs are worndown，compared to the stomachs of healthy bees,” Evans says.It may be that aparasite is damaging the bees digestive organs. Their immune systems may not be working as they should.Moreover，they have high levels of bacteria inside theirbodies.
Another cause of colony-collapse disorder may be certain chemicalsthat farmers apply to kill unwanted insects on crops，says Jerry Hayes，chief beeinspector for the Florida Department of Agriculture3.Some studies，hesays，suggest that a certain type of insecticide affects the honeybee’s nervoussystem (which includes the brain) and memory.”It seems tike honeybees are goingout and getting confused about where to go and what to do,” he says.
If itturns out that a disease is contributing to colony collapse，bees genes couldexplain why some colonies have collapsed and others have not.In any group ofbees there are many different kinds of genes.The more different genes a grouphas，the higher the group’s genetic diversity.So far scientists haven’tdetermined the role of genetic diversity in colony collapse，but it’s a promisingtheory，says Evans.
41. What is the mystery that researchers find hard to explain?
A. Honeybees are flying all across the country.
B. 25—40 percent of the honeybees in the US have died.
C. Honeybees are leaving their hives and do not return.
D. Honeybee hives are in disorder.
42. Why are researchers seriously concerned with the phenomenon of colony-collapse disorder?
A. Because honeybees produce one-third of the foods we eat
B. Because honeybees feed on flowers.
C. Because honeybees eat seeds of flowers.
D. Both B and C.
43. What are the possible causes of colony-collapse disorder given by the scientists?
A. Worsening environment.
B. Disease and chemicals.
C. Dwindling number of flowers around.
D. Changes in genes' structures.
44. According to the fifth paragraph, which of the following about bees' genes is true?
A. Bees' genes allow them to expand their colonies.
B. Bees' genes help keep them in their hives.
C. Bees' genes make them fly from flower to flower.
D. Bees' genes could explain the collapse of some colonies.
45. What explanation is given by Jerry Hayes to the phenomenon?
A. Farmers apply certain chemicals to kill unwanted bees.
B. The insecticide destroys the honeybee's nervous system.
C. The insecticide affects the honeybee's memory.
D. All of the above.
