完形填空（共15小题；每小题2分，满分30分）

阅读下面短文，掌握其大意，然后从下列各题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题卡上将该项涂黑。

The human nose is an underestimated tool. Humans are often thought to be  1___ smellers compared with animals, but this is largely because, unlike animals, we stand upright. This means that our noses are  2  to detecting those smells which float through the air,  3  the majority of smells which stick to surfaces. In fact though, we are extremely sensitive to smells, even if we do not generally realize it. Our noses are capable of  4  human smells even when these are  5  to far below one part in one million.

　　  6     , some people find that they can smell one type of flower but not another, while others are sensitive to the smells of both flowers. This may be because some people do not have the genes necessary to generate  7     smell receptors in the nose. These receptors are the cells which sense smells and send  8    to the brain. However, it has been found that even people insensitive to a certain smell at first can suddenly become sensitive to it when  9     to it often enough.

　　The  10   for insensitivity to smell seems to be that brain finds it  11    to keep all smell receptors working all the time but can  12   new receptors if necessary. This may also explain why we are not usually sensitive to our own smells we simply do not need to be. We are not  13     of the usual smell of our own house but we  14     new smells when we visit someone else's. The brain finds it best to keep smell receptors _ 15    for unfamiliar and emergency signals such as the smell of smoke, which might indicate the danger of fire.

Since the beginning of history, man has been attracted by the idea of living forever, of winning the fight against death and disease. So far, this has only remained a dream. Many people have wondered whether it would be possible to find a way to preserve human bodies, and what would be the best way.
It has long been known that meat of fruit can be kept fresh for long periods by freezing; in ancient China, for example, food was stored with ice to keep it fresh. This method could also be useful for preserving humans.
However, most living beings that exist under warm conditions die when frozen. This is because of the harmful effects of freezing ice crystals(晶体), which not only are larger than the volume(体积) of the water originally in the cells, but also form sharp cutting shapes that harm the cells.
In the 1940s Dr B.J. Luyet and a group of scientists in England were working on the problem of freezing cells without damaging them. Since the harm caused by ice crystals was the main cause of damage, Luyet suggested removing some or all of the water from the cells before freezing them.
Using living cells form chicken, Luyet and his assistants discovered that they could partly dry the chicken cells, using a mixture of the white part of an egg and glycerin (丙三醇). Some success was obtained. The chicken cells were dried, frozen for a period of time, and then carefully unfrozen. Almost all the cells recovered when they reached normal temperatures.
Since then, the cooling of whole animals to a temperature far below freezing point for later unfreezing has become more of a possibility, and the glycerin method would probably be used to accomplish this. When this can be done completely and successfully, science will have moved much closer to its aim of freezing and storing incurable patients until the day they can be cured.
【小题1】What does the passage mainly talk about?

Passage six(Dropouts for Ph. D. s)
Educators are seriously concerned about the high rate of dropouts among the doctor of philosophy candidates and the consequent loss of talent to a nation in need of Ph. D. s. Some have placed the dropouts loss as high as 50 percent. The extent of the loss was, however, largely a matter of expert guessing. Last week a well-rounded study was published. It was published. It was based on 22,000 questionnaires sent to former graduate students who were enrolled in 24 universities and it seemed to show many past fears to be groundless.
The dropouts rate was found to be 31 per cent, and in most cases the dropouts, while not completing the Ph. D. requirement, went on to productive work. They are not only doing well financially, but, according to the report, are not far below the income levels of those who went on to complete their doctorates.
Discussing the study last week, Dr. Tucker said the project was initiated ‘because of the concern frequently expressed by graduate faculties and administrators that some of the individuals who dropped out of Ph. D. programs were capable of competing the requirement for the degree. Attrition at the Ph. D. level is also thought to be a waste of precious faculty time and a drain on university resources already being used to capacity. Some people expressed the opinion that the shortage of highly trained specialists and college teachers could be reduced by persuading the dropouts to return to graduate schools to complete the Ph. D.’
“The results of our research” Dr. Tucker concluded, “did not support these opinions.”
Lack of motivation was the principal reason for dropping out.
Most dropouts went as far in their doctoral program as was consistent with their levels of ability or their specialities.
Most dropouts are now engaged in work consistent with their education and motivation.
Nearly 75 per cent of the dropouts said there was no academic reason for their decision, but those who mentioned academic reason cited failure to pass the qualifying examination, uncompleted research and failure to pass language exams. Among the single most important personal reasons identified by dropouts for non-completion of their Ph. D. program, lack of finances was marked by 19 per cent.
As an indication of how well the dropouts were doing, a chart showed 2% in humanities were receiving $ 20,000 and more annually while none of the Ph. D. ‘s with that background reached this figure. The Ph. D. ‘s shone in the $ 7,500 to $ 15,000 bracket with 78% at that level against 50% for the dropouts. This may also be an indication of the fact that top salaries in the academic fields, where Ph. D. ‘s tend to rise to the highest salaries, are still lagging behind other fields.
As to the possibility of getting dropouts back on campus, the outlook was glum. The main condition which would have to prevail for at least 25 % of the dropouts who might consider returning to graduate school would be to guarantee that they would retain their present level of income and in some cases their present job.
1.The author states that many educators feel that
A.steps should be taken to get the dropouts back to campus.
B.the fropouts should return to a lower quality school to continue their study.
C.the Ph. D. holder is generally a better adjusted person than the dropout.
D.The high dropouts rate is largely attributable to the lack of stimulation on the part of faculty members.
2.Research has shown that
A.Dropouts are substantially below Ph. D. ‘s in financial attainment.
B.the incentive factor is a minor one in regard to pursuing Ph. D. studies.
C.The Ph. D. candidate is likely to change his field of specialization if he drops out.
D.about one-third of those who start Ph. D. work do not complete the work to earn the degree.
3.Meeting foreign language requirements for the Ph. D.
A.is the most frequent reason for dropping out.
B.is more difficult for the science candidate than for the humanities candidate.
C.is an essential part of many Ph. D. programs.
D.does not vary in difficulty among universities.
4.After reading the article, one would refrain from concluding that
A.optimism reigns in regard to getting Ph. D. dropouts to return to their pursuit of the degree.
B.a Ph. D. dropout, by and large, does not have what it takes to learn the degree.
C.colleges and universities employ a substantial number of Ph. D. dropouts.
D.Ph. D. ‘s are not earning what they deserve in nonacademic positions.
5.It can be inferred that the high rate of dropouts lies in
A.salary for Ph. D. too low.
B.academic requirement too high.
C.salary for dropouts too high.
D.1000 positions.

Few laws are so effective that you can see results just days after they take effect.But in the nine days since the federal cigarette tax more than doubled－to $1.01 per pack－smokers have jammed telephone “quit lines” across the country seeking to kick the habit.

This is not a surprise to public health advocates.They've studied the effect of state tax increases for years，finding that smokers，especially teens，are price sensitive.Nor is it a shock to the industry，which fiercely fights every tax increase.

The only wonder is that so many states insist on closing their ears to the message.Tobacco taxes improve public health，they raise money and most particularly，they deter people from taking up the habit as teens，which is when nearly all smokers are addicted.Yet the rate of taxation varies widely.

In Manhattan，for instance，which has the highest tax in the nation，a pack of Marlboro Light Kings，cost $10.06 at one drugstore Wednesday.In Charleston，S.C.，where the 7 cent a pack tax is the lowest in the nation，the price was $4.78.

The influence is obvious.

In New York，high school smoking hit a new low in the latest surveys－13.8%，far below the national average.By comparison,26% of high school students smoke in Kentucky.Other low tax states have similarly depressing teen smoking records.

Hal Rogers，Representative from Kentucky，like those who are against high tobacco taxes，argues that the burden of the tax falls on low?income Americans “who choose to smoke.”

That's true.But there is more reason in keeping future generations of low?income workers from getting hooked in the first place.As for today's adults，if the new tax drives them to quit，they will have more to spend on their families，cut their risk of cancer and heart disease and feel better.

1.The text is mainly about ________.

A．the price of cigarettes

B．the rate of teen smoking

C．the effect of tobacco tax increase

D．the differences in tobacco tax rate

2.What can we learn from the last paragraph?

A．The new tax will be beneficial in the long run.

B．Low?income Americans are more likely to fall ill.

C．Future generations will be hooked on smoking.

D．Adults will depend more on their families.

3.Rogers' attitude towards the low?income smokers might be that of ________.

A．tolerance? ????????????? ????????????? ????????????? B．unconcern?

C．doubt? ????????????? ????????????? ????????????? ????????????? D．sympathy

4.What does the author think is a surprise?

A．Teen smokers are price sensitive.

B．Some states still keep the tobacco tax low.

C．Tobacco taxes improve public health.

D．Tobacco industry fiercely fights the tax rise.

根据短文内容，从下边的A—F选项中选出能概括每一段主题的最佳选项。选项中有一项为多余选项。

A . The different structure of blue holes.????????

B. Why scientists are interested in blue holes.????????

C. How a blue hole comes into being.

D. Blue holes exploring is becoming popular.

E. Rules to obey when diving into blue holes.

F. The general definition of a blue hole.

1.______________

??? A blue hole is a flooded sea cave with a hole that opens up at the land's surface. These cave systems form in carbonate rock, often on islands. Some blue holes have very special rock formations and water chemistry. Far below sea level, they contain some of the harshest environments on Earth, with no oxygen and no light. Yet these areas are filled with life forms that have adapted to the extreme conditions.

2.___________

??? Blue holes get their name from the color some have when seen from the air. The color is usually a reflection of the sky on the water. Blue holes are the result of erosion in which water breaks down rock. Rain falling thousands of years ago contained chemicals which slowly wore away at the limestone landmass. These holes later filled with sea water as the sea level changed. The rising and falling of sea levels and the mixture of salt and fresh water further wore away at these cave formations.

3.___________

??? These flooded cave systems can be found in the ocean, or they can be found inland. Ocean caves are affected by tides, so they always have water movement. But blue holes on land are very still. They have several layers of water, chemicals, and bacteria. The top layer of fresh water comes from rainfall. This layer acts like a cap on top of the layered mixture, and keeps out oxygen from the atmosphere. The fresh water floats on a denser layer of saltwater. Underneath this is a layer of poisonous hydrogen sulfide, produced by bacteria living in the water. Underneath this layer is anoxic seawater -- water that does not contain any oxygen.

4.___________

??? Information gathered from these blue holes is helping scientists to increase their understanding of biology, archaeology and geology. But exploring these blue hole environments brings danger as well as discovery. Scientists are interested in these caves because oxygen-free conditions there are similar to those on Earth long ago, before oxygen existed on our planet. But there are many difficulties involved in diving into blue holes.

5.___________

One reason blue holes have not been fully explored is that they can be extremely dangerous. There are many safety rules that divers must follow to help ensure their survival. First, divers must have training and experience to swim in these caves. Divers who explore a cave for the first time must establish a thin rope called a guideline. This line helps them to safely enter and exit the cave without getting lost.