such as sucrose consists of two chemically bonded monosaccharide which are cleaved during digestion.

The topic of cloning has been a politically and ethically controversial one since its very beginning. While the moral and philosophical aspects of the issues are entirely up to the interpretation of the individual, the application of cloning technology can be studied objectively. Many in the scientific community advocate the use of cloning for the preservation and support of endangered species of animals, which aside from cloning, have no other practical hope for avoiding extinction.

The goal of the use of cloning to avoid extinction is the reintroduction of new genes into the gene pool of species with few survivors, ensuring the maintenance and expansion of genetic diversity. Likely candidates for this technique are species known to have very few surviving members, such as the African Bongo Antelope, the Sumatran Tiger, and the Chinese Giant Panda. In the case of Giant Panda, some artificial techniques for creating offspring have already been performed, perhaps paving the way for cloning as the next step in the process.

With the estimated population of only about 1000 Giant Pandas left in the world, the urgency of the situation has led to desperate measures. One panda was born through the technique of artificial insemination in the San Diego Zoo in the United States. "Hua Mei" was born in 1999 after her parents, Hsing-Hsing and Ling-Ling, had trouble conceiving naturally.

The plan to increase the Giant Panda population through the use of cloning involves the use of a species related to the Giant Panda, the American Black Bear. Egg cells will be removed from female black bears and then fertilized with Panda cells such as those from Ling-Ling or Hsing-Hsing. The fertilized embryo will then re-implanted into the black bear, where it will grow and mature, until a new panda is delivered from the black bear host.

Critics of cloning technology argue that the emphasis on cloning as a method by which to preserve species will draw funding away from other methods, such as habitat preservation and conservation. Proponents of cloning counter that many countries in which many endangered species exist are too poor to protect and maintain the species' habitats anyway, making cloning technology the only practical way to ensure that those species survive to future generations. The issue is still hotly debated, as both sides weigh the benefits that could be achieved against the risks and ethical concerns that constantly accompany any argument on the issue.

Notes:

ethically 道德上。gene pool 基因库。insemination n.受精。fertilize 使受精。embryo 胚胎。proponent支持者，拥护者。weigh A against B权衡A和B的利弊。

The author raises the issue of ethical consideration in cloning in paragraph 1 in order to _____.

A．identify the issues that will not be addressed in the text.

B．reveal an area of interest that will be explored later in the text.

C．identify one of the main issues affecting the cloning controversy today.

D．draw the reader's attention to a sensitive issue that bears consideration in the topic of cloning.

The topic of cloning has been a politically and ethically controversial one since its very beginning. While the moral and philosophical aspects of the issues are entirely up to the interpretation of the individual, the application of cloning technology can be studied objectively. Many in the scientific community advocate the use of cloning for the preservation and support of endangered species of animals, which aside from cloning, have no other practical hope for avoiding extinction.

The goal of the use of cloning to avoid extinction is the reintroduction of new genes into the gene pool of species with few survivors, this ensuring the maintenance and expansion of genetic diversity. Likely candidates for this technique are species known to have very few surviving members, such as the African Bongo Antelope, the Sumatran Tiger, and the Chinese Giant Panda. In the case of Giant Panda, some artificial techniques for creating offspring have already been performed, perhaps paving the way for cloning as the next step in the process.

With the estimated population of only about 1000 Giant Pandas left in the world, the urgency of the situation has led to desperate measures. One panda was born through the technique of artificial insemination in the San Diego Zoo in the United States. "Hua Mei" was born in 1999 after her parents, Hsing-Hsing and Ling-Ling, had trouble conceiving naturally.

The plan to increase the Giant Panda population through the use of cloning involves the use of a species related to the Giant Panda, the American Black Bear. Egg cells will be removed from female black bears and then fertilized with Panda cells such as those from Ling-Ling or Hsing-Hsing. The fertilized embryo will then re-implanted into the black bear, where it will grow and mature, until a new panda is delivered from the black bear host.

Critics of cloning technology argue that the emphasis on cloning as a method by which to preserve species will draw funding away from other methods, such as habitat preservation and conservation. Proponents of cloning counter that many countries in which many endangered species exist are too poor to protect and maintain the species' habitats anyway, making cloning technology the only practical way to ensure that those species survive to future generations. The issue is still hotly debated, as both sides weigh the benefits that could be achieved against the risks and ethical concerns that constantly accompany any argument on the issue.

Notes:

ethically 道德上

gene pool 基因库

insemination n. 受精

fertilize 使受精

embryo 胚胎

proponent 支持者，拥护者

weigh A against B权衡A和B的利弊

The author raises the issue of ethical consideration in cloning in paragraph 1 in order to

A．identify the issues that will not be addressed in the text.

B．reveal an area of interest that will be explored later in the text.

C．identify one of the main issues affecting the cloning controversy today.

D．draw the reader's attention to a sensitive issue that bears consideration in the topic of cloning.

Man, even in the lower stages of development, possesses a faculty which, for want of a better name, I shall call Number Sense. This faculty permits him to recognize that something has changed in a small collection when, without his direct knowledge, an object has been removed from or added to the collection.

Number sense should not be confused with counting, which involves a rather intricate mental process. Counting, so far as we know, is an attribute exclusively human, whereas some animal species seem to possess an elementary number sense similar to our own. At least, such is the opinion of competent observers of animal behavior, and the theory is supported by a weighty nass of evidence.

Many birds, for instance, possess such a number sense, If a nest contains four eggs, one can safely be taken; but when two are removed, the bird generally deserts. In some unaccountable way the bird can distinguish two from three. But this faculty is by no means confined to birds, most striking instance we know is that of the insect called the "solitary wasp." The mother wasp lays her eggs in individual cells and provides each egg with a number of live caterpillares (毛虫) on which the young feed when hatched. Now, the number of victims is remarkably constant for a given species of wasp. Some species provide 5, others, 12, others again as high as 24 caterpillars per cell. But most remarkable is the case of the Genus Eumenus, a variety in which the male is much smaller than the female. In some mysterious way the mother knows whether the egg will produce a male or a femalc and divide the quantity of food accordingly; she does not change the species or size of the prey, but if the egg is male, she supplies it with five victims; if female, with teem.

The regularity in the action of the wasp makes this last case less convincing than the one which follows. Here the action of the bird seems to border on the conscious.

A landowner was determined to shoot a crew which made its nest in the watchtower of his estate. Repeatedly he tried to surprise the bird. But in vain: at the approach of man the crow would leave its nest. From a distant tree it would watchfully wait until the man had left the tower and then return to its nest. One day the landowner hit upon an idea: two men entered the tower, one remained within, the other came out and went on. But the bird was not deceived: it kept away until the man within came out. The experiment was repeated on the succeeding days with two, three, then four men, yet without success. Finally, five men were sent: as before, all entered the tower, and one remained while the other four came out and went away. Here the crow lost count. Unable to distinguish between four and five, it promptly returned to its nest.

The main idea of this passage is that ______.

A．man's elementary number sense is found in lower species

B．birds have a limited number sense

C．animals cannot count

D．number sense is a primitive form. of counting

Before 1965 many scientists pictured the circulation of the ocean's water mass as consisting of large slow-moving currents, such as the Gulf Stream. That view, based on 100 years of observations made around the globe, produced only a rough approximation of the true circulation. But in the 1950s and the 1960s, researchers began to employ newly developed techniques and equipment including subsurface floats that move with ocean current and emit identification signals for months at fixed locations in the ocean. These instruments disclosed an unexpected level of variability in the' deep ocean. Rather than being characterized by smooth, large-scale currents that change seasonally (if at all), the seas are dominated by what oceanographers (海洋研究者) call mesoscale fields (紊流): fluctuating, energetic flows whose velocity can reach ten times of the mean velocity of the majior currents.

Mesoscale phenomena--the oceanic analogue of weather terms--often extend to distances of 100 kilometers and persist for 100 days (weather systems generally extend about 1 000 kilometers and last 3 to 5 days in any given area). More than 90 percent of the kinetic energy of the entire ocean may be accounted for by mesoscale variability rather than by large-scale currents. Mesoscale phenomena may, in fact, play a significant role in oceanic mixing air-sea interactions, and' occasional but far-reaching climate events such as EI Nino ,the atmospheric-oceanic disturbance in the equatorial Pacific that affects global weather patterns.

Unfortunately, it is not feasible to use conventional techniques to measure mesoscale fields. To measure them properly, monitoring equipments would have to be laid out on a grid at intervals of at most 50 kilometers, with sensors at each grid point lowered deep in the ocean and kept there for many months. Because using these techniques would be prohibitively expensive and time-consuming, it was proposed in 1975 that tomography (X射线断层摄影技术) be adapted to measuring the physical properties of the ocean. In medical tomography X-rays map the human body's density variations (and hence internal organs); the information from the X-rays, transmitted through the body along many different paths, is recombined to form. three-dimensional images of the body's interior. It is primarily this multiplicative increase in data obtained from the multi-path transmission of signals that accounts for oceanographers' attraction to tomography: it allows the measurement of vast areas with relatively few instruments. Researchers reasoned that low-frequency sound waves ,because they are so well described mathematically and because even small perturbations(动摇) in emitted sound waves can be detected, could be transmitted through the ocean over many different paths and that the properties of the ocean's interior-its temperature, salinity, density and speed of currents-could be deduced on the basis of how the ocean altered the signals. Their initial trials were highly successful, and ocean acoustic tomography was born.

Which of the following is TRUE according to Para. 1?

A．Nowadays, scientists pictured the circulation of ocean's water mass as consisting of large slow-moving currents.

B．Before 1965 ,the concept of scientists produced only a rough approximation of the true circulation.

C．Researchers began to do research on the developed techniques and equipment.

D．These instruments disclosed an expected level of variability in the deep ocean.

听力原文： I flew to San Francisco to take care of some business with Mr. Jordan. But as soon as I arrived. I got sick and couldn't meet with him. I had to call our appointment off. Then, when I felt better I thought about visiting him at his home, but he lived too far away. I tried to telephone him during office hours, but he was busy. The receptionist said that Mr. Jordan would call me back, but he didn't. I gave up trying to make a new appointment because it would take more time and effort than I wanted to spend. A few days later, I saw a man on the street who looked like Mr. Jordan, and I called out to him. It was someone else. When I returned to my hotel that day, I found a message, which said that Mr. Jordan had gone out of town on some sudden unexpected business. I was sorry I really missed seeing him, but I really enjoyed my sightseeing in San Francisco.

(23)

A．He missed the appointment.

B．He arrived late.

C．He was sick.

D．He was very busy.

听力原文： I flew to San Francisco to take care of some business with Mr. Jorden. But as soon as I arrived, I got sick and couldn ' t meet with him. I had to call our appointment off. Then when I felt better, I thought about visiting him at his home, but he lived too far away. I tried to telephone him during office hours but he was busy. The receptionist said that Mr. Jarden would call me back. But he didn't. I gave up trying to make a new appointment because it would take more time and effort than I wanted to spend. A few days later, I saw a man on the street who looked like Mr. Jorden and I called out to him. It was someone else. When I returned to my hotel that day, I found a massage which said that Mr. Jarden had gone out of town for some sudden unexpected business. I was sorry I had missed seeing him. But I really enjoyed my sightseeing in San Francisco.

(31)

A．He missed the appointment.

B．He arrived late.

C．He was sick.

D．He was very busy.