ed up ______.

sum．

A.Be secured

B.Be sincere

C.Be simulated

D.Be signature

bly ______

A．be punished by a large sum of fine.

B．lose the right to operate for a period.

C．be forced to report news that do not please advertisers and consumers.

D．have no punishment at all.

A、Wait until the public announcement is made,then release a report explaining that he believes the company will make the release date;disclosing that one of the reasons for his opinion is Perry is a friend of his.

B、Produce his research report in two days based solely on the official announcement,not taking into consideration the information from Perry.

C、Wait until the public announcement is made,then releasing a report stating that he is sure that the company will make his release date,but not disclose the relationship with Perry.

utes, followed by a slowly declining release rate over several months. The total release is estimated to have been about 5×10⁷curies The winds carried the released materials all the way to Sweden, from which the first reports came that there had been a nuclear accident in the USSR.

For the purposes of this problem assume that there was an instantaneous release of 10⁷curies of radioactive gases (and fine particles, which are assumed to remain in the atmosphere and not settle out). Then estimate the maximum ground level concentration of radioactive gases (curies/m³) when the radioactive cloud from the accident got to Sweden. Make the following assumptions:

(1) Ignore decay of the radioactive gases (i.e., assume their half-lives were infinite).

(2) Assume the distance between Chernobyl and Sweden is 1000 km.

(3) Assume that the wind speed was 3 m/s and the stability class C.

(4) Assume that the mixing height was 2000 m.

(5) Assume that mlXmg in the x direction(up and down the direction of the wind) has the same intensity as miXing in the y(crosswind)direction.

of fossil fuels will not, in fact, result in a greenhouse effectan increase in average global temperatures. Since plants use carbon dioxide in larger quantities if the supply is increased, they are able to grow larger and multiply more vigorously, and atmospheric carbon dioxide concentrations will eventually become stable. Which of the following, if true, would most seriously weaken the conclusion that a greenhouse effect will not result from the current release of large amounts of carbon dioxide into the atmosphere？

A．The expected rise in average global temperatures has not yet been observed.

B．Ocean waters absorb carbon dioxide at a greater rate when the atmospheric concentration of carbon dioxide is higher.

C．Since the beginning of the Industrial Revolution, increased atmospheric concentrations of carbon dioxide have resulted in improved agricultural productivity.

D．When plants decay, they produce methane, another gas that can have a marked greenhouse effect.

E．The fact that carbon dioxide levels have risen and fallen many times in the Earth"s history suggests that there is some biological process that can reverse the greenhouse effect.

here in the body. In recent studies, however, we have discov- ered that the production and release in brain neurons of the neurotransmitter serotonin(neurotransmitters are compounds that neurons use to transmit signals to other cells)depend directly on the food that the body processes. Our first studies sought to determine whether the increase in serotonin observed in rats given a large injection of the amino acid tryptophan might also occur after rats ate meals that change tryptophan levels in the blood. We found that, immediately after the rats began to eat, parallel elevations occurred in blood tryptophan, brain tryptophan, and brain serotonin levels. These findings suggested that the production and release of serotonin in brain neurons were normally coupled with blood-tryp-tophan increases. In later studies we found that injecting insulin into a rats bloodstream also caused parallel elevations in blood and brain tryptophan levels and in serotonin levels. We then decided to see whether the secretion of the animals own insulin similarly affected serotonin production. We gave the rats a carbohydrate-containing meal that we knew would elicit insulin secretion. As we had hypothesized, the blood trypto- phan level and the concentrations of tryptophan serotonin in the brain increased after the meal. Surprisingly, however, when we added a large amount of protein to the meal, brain tryptophan and serotonin levels fell. Since protein contains tryptophan, why should it depress brain tryptophan levels？ The answer lies in the mechanism that provides blood tryp- tophan to the brain cells. This same mechanism also provides the brain cells with other amino acids found in protein, such as tyrosine and leucine. The consumption of protein increases blood con- centration of the other amino acids much more, proportionately, than it does that of tryptophan. The more protein in the meal, the lower is the ratio of the resulting blood-tryptophan concentration to the concentration of competing amino acids, and the more slowly is tryptophan provided to the brain. Thus the more protein in a meal, the less serotonin subsequently produced and re- leased.

Which of the following titles best summarizes the contents of the passage？

A．Neurotransmitters: Their Crucial Function in Cellular Communication

B．Diet and Survival: An Old Relationship Reexamined

C．The Blood Supply and the Brain: A Reciprocal Dependence

D．Amino Acids and Neurotransmitters: The Connection Between Serotonin Levels and Tyrosine

E．The Effects of Food Intake on the Production and Release of Serotonin: Some Recent Findings

recently the very【58】of the bank building was designed to【59】people that their money would be safe. There were thick, solid walls and barred windows. All the windows and doors were wired to set 【60】the burglar alarms if anyone tried to【61】his way in.

The vaults where his money was kept had huge, steel doors with【62】locks.【63】guards with pistols in their holsters were always on【64】in the bank. The tellers cages----the cubicles 【65】the bank clerks, or tellers, worked-actually.【66】 cages. They had gratings across the front, high sides and back, and a door that could be opened only by pushing a release button.

The new style. of bank design【67】some of these【68】features, but the idea now is to make the bank【69】 like a friendly place【70】than a forbidding fortress. The modem bank buildings are open and light,【71】large glass windows and doors. The tellers' cages have been【72】by flat, unobstructed counters. The【73】and burglar alarms are still there, but they are【74】noticeable than they【75】to be.

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A．a(chǎn)nd

B．but

C．that

D．what

What Causes Earthquakes？

People have tried to explain the cause of earthquakes since earliest times. Some people thought that quakes were sent from heaven to punish the wicked. Others believed that the earth rested on the backs of animals. We now have more scientific explanations of the cause of these destructive earth tremors. Earthquakes are evidence that some process is at work below the surface of the earth. Large bodies of magma may be in motion. These and other internal movements can result in a sudden release of energy by breaking the overlying, brittle rocks. During earthquakes, rocks beneath the surface are clearly bent and broken. In other cases deformation takes place slowly and without recognizable earthquake shocks. For example, in a drill hole in the Great Valley of California, earth movements have been measured for years. The rocks here are moving at a rote of about one meter per century. In some places pressure slowly builds up until the rocks break and quickly snap back into position. The faulting releases energy that may have built up in the rocks for hundreds or thousands of years. This sudden burst of energy causes vibrations that travel through the rocks. These vibrations are an earthquake. Most earthquakes are so small that they can be detected only by sensitive instruments along the fault surface. However, energy may continue to trickle off in aftershocks. These shocks are much less severe than the main shock and may continue for months after the initial earthquake.

Summary:

Scientifically speaking, earthquakes are caused when【71】movements of the earth suddenly release energy by breaking the overlying rocks on the surface. During earthquake, rocks are clearly bent and broken. Elsewhere, rocks may slowly【72】over many years. Then the pressure may increase until the rocks break and snap back. This break【73】the energy in the rocks and causes vibrations. Most earthquakes are so small that they can be barely【74】, but large violent earthquakes can destroy inhabited areas. Sometimes【75】many follow after the first movement.

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sphere. One potentially inexpensive and self-sustaining countermeasure is to introduce natural enemies of the plant; therefore, some scientists have proposed to control bracken by a release of bracken-eating moths native to the Southern Hemisphere into bracken-infested areas in the Northern Hemisphere. If the scientists proposal for controlling bracken is adopted, which of the following is a necessary condition for its success？

A．That bracken in the Northern Hemisphere grows in approximately the same climates and soil conditions in which it grows in the Southern Hemisphere.

B．That the released moths will feed on weeds other than bracken that are native to the Northern Hemisphere.

C．That the livestock that will return to pastures now lost to bracken will develop immunities to the diseases caused by bracken.

D．That the released moths will survive in sufficient numbers to build a population large enough to reduce bracken and retard its growth.

E．That traditional methods of control, such as burning, cutting, and chemical spraying, will not become less expensive or labor-intensive than they are now.