题目内容
Section B
Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D.
听力原文： Experts say some farming activities are seriously damaging Earth's environment. Bad farming methods can damage soil, forests and water supplies. They also have caused some plants and animals to disappear.
Two groups now say that bad farming methods are threatening the ability of farmers to produce enough food to feed the world population in the future.
The groups used satellite images, maps and modern equipment to study the effect of agriculture on the environment. The study found that the destruction of soil is widespread. Important organic nutrients
are being removed from farmland.
Agriculture uses seventy percent of the freshwater in the world each year. The study found that many farmers are wasting water supplies. In addition, chemicals designed to protect crops may pollute waterways.
The report also says as much as thirty percent of the world's forests have been cut down so the land could be used for agriculture. This has led to a severe loss of wildlife and their environments.
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Foods That Fight Disease
With remarkable consistency, recent research has found that a diet high in plant -based foods—fruits, vegetables, dried peas and beans, grains, and starchy staples such as potatoes — is the body's best weapon in thwarting many health - related problems. These foods work against so many diseases that the same healthy ingredients you might use to protect your heart or ward off cancer will also benefit your intestinal tract and bones.
Here's what is currently known about these different disease -fighting foods. Cancer Fighters
Preventing cancer is a compelling reason to load up your cart in the produce department. Scientists have recently estimated that approximately 30 to 40 percent of all cancers could be averted if people ate more fruits, vegetables, and plant - based foods and minimized high -fat, high -calorie edibles that have scant nutritional value. Up to 70 percent of cancers might be eliminated if people also stopped smoking, exercised regularly, and controlled their weight.
In the past, researchers had linked fat consumption with the development of cancers, but they currently believe that eating fruits, vegetables, and grains may be more important in preventing the disease than not eating fat. "The evidence about a high- fat diet and cancer seemed a lot stronger several years ago than it does now," says Melanie Polk, a registered dietitian and director of nutrition education at the American Institute for Cancer Research.
Although scientists are still not certain about the specifics, they're beginning to close in on the healthful constituents of plant- based foods. In particular, they're looking closely at two components antioxidants and phytochemicals.
Antioxidants. The antioxidants (carotenoids, such as beta carotene and lycopene, and vitamins C and E) found in fruits, vegetables, and other plant -based foods fight free radicals, which are compounds in the body that attack and destroy cell membranes. The uncontrolled activity of free radicals is believed to cause many cancers.
The carotenoids, in particular, which give fruits and vegetables their bright yellow, orange, and red colors, are now gaining recognition for their nutritional worth. Numerous studies have extolled the virtues of lycopene (the carotenoid that makes tomatoes red) in preventing prostate cancer. One such study at Harvard University found that men who include tomato products in their meals twice a week could reduce their risk of developing prostate cancer by one third compared with men who never touch tomatoes.
Other lycopene - rich foods, such as watermelon, red grapefruit, and guava, are now piquing the interest of researchers. Watermelon not only yields more lycopene per serving (15 mg in 11/2 cups) than raw tomatoes (11 mg per 11/2 cups), but it's also a rich source of vitamins A and C.
Can watermelon help reduce the incidence of cancer？ No one knows for sure because there haven' t been sufficient studies. "We assume that we'll see benefits," says Penelope Perkins Veazie, Ph. D., a research scientist with the USDA's Agricultural Research Service. Researchers there plan to compare people who eat watermelon with those who eat processed tomatoes because cooking enhances lycopene absorption—o see which group absorbs more lycopene. (A 11/2 cup serving of tomato sauce packs 53 mg of lycopene. )
Phytochemicals. The phytochemicals present in fruits and vegetables protect the body by stunting the growth of malignant cells. Phytochemicals, naturally occurring substances, include indoles ([生化]吲哚) in cabbage or cauliflower, saponins ([生化]皂角苷 ) in peas and beans, and isoflavones (异黄酮) in soy milk and tofu. Investigators have only an inkling of how many phytochemicals exist and how they work. They are confident, however, that you can get a basketful of anti- cancer nutrients by mi
SECTION 4
Directions: Each question below consists of a word printed in capital letters followed by five lettered words or phrases. Choose the lettered word or phrase that is most nearly opposite in meaning to the word in capital letters. Since some of the questions require you to distinguish fine shades of meaning, be sure to consider all the choices before deciding which one is best.
BOYCOTT :
Darwin proposed the theory of sexual selection to explain the origin of ostentatious
plumage in certain bird species, maintaining that the ornate features of males are a
consequence of female mate selection based on an
Line abstract aesthetic sense, not unlike the process of animal breeders producing
(5) fancy-male varieties of pigeons by conscious artificial selection. Wallace
suggested an alternative explanation: through greater physical energy the most
highly adorned males are able to win the competition with rival males.
Meanwhile Huxley pointed out that male adornment is instrumental in
establishing dominance relationships among males: adornment reduces the
(10) physical activity necessary to intimidate rivals.
However, Jacobs later examined the process of female choice, concluding
that what appeared to be choice of an adorned male by a female was really a
mutual attraction to a certain reproductive site. Mate selection requires an
awareness of features characteristic of a suitable breeding site, which might be
(15) mirrored in the ornamentation of the male, and thus mate selection is related
directly to adaptive niche specialization. From this insight, Austin proceeded to
develop a food-courtship theory of mate selection: the population most efficient
in use of the energy available in a particular niche will be the fittest to survive
there. Through natural selection, organisms will tend to become specialized to
(20) form. isolated populations, each adapted to utilize the energy most efficiently
that is available in a particular niche and this process of segregation and
specialization of populations is facilitated by employing in the mating process
samples of the food available in the preferred niche. In particular cases, the
male may display the food to the female or feed it to her in the courtship
(25) ceremony, maybe bearing permanent representations of specific foods on his
plumage, and the female may be attracted to the male for these representations
of the territorial foods.
Austin's theory may be applied to the case for mate choice among
peafowls, whose males' "eyespotted" tail feathers bear a striking resemblance
(30) to blue berries. According to the food-courtship theory, it is because their
plumage bears representations of food that peacocks attract peahens, which may
explain why males with the most "eyespots" on their tail have the greatest
mating success. Not inconsistent with a possible role of the "eyespots" in
reproductive competition among males and in aesthetic selection, this
(35) explanation seems more plausible than the suggestion that by selecting mates
according to the perfection of their tail-feather "eyespots", peahens are able to
identify mates with the greatest "fitness". This process, bringing together
males and females of similar tastes and physiologies, may lead to speciation.
Some of the male display features may come to be involved in species
(40) identification, and it has also been noted that male adornment could have a dual
function, repelling rival males as well as attracting females.
The passage is primarily concerned with
The passage mentions that at various points, scientists have believed all of the following
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