All the aquatic mammals sleep a lot.A.RightB.WrongC.Not mentioned
All the aquatic mammals sleep a lot.
A.Right
B.Wrong
C.Not mentioned
All the aquatic mammals sleep a lot.
A.Right
B.Wrong
C.Not mentioned
According to Sandra Postel, which one is NOT correct?
A. Freshwater only accounts for 2.5% of all water on Earth.
B. Only one third of the freshwater is not stocked in glaciers and ice caps.
C. Most freshwater does not participate in the water cycle.
D. The aquatic environment will be damaged if people still pump groundwater.
The problem of municipal sewage disposal is complicated by the fact that, years ago, most cities combined their storm and waste disposal sewers. Many of these combined systems work well, but others cannot cope with sudden heavy rains. When such storms occur, water mixed with sewage may flood and disable treatment plants unless bypassed, untreated, into a stream. In either case, the people may have little protection for several days from these wastes that may contain disease germs.
One consequence of pollution, usually resulting from the discharge of either raw or treated sewage wastes into water sources, is an increase in nutrient levels in these waters. These higher nutrient levels result in a rapid increase in the biological population of the water. Excessive respiration and decomposition of aquatic plants deplete the oxygen content in these waters causing decay which, in turn, may produce an undesirable taste, odor, color and turbidity. Increasing nutrient contents may also result in an in- crease in more undesirable species of aquatic life. All these factors make the water un- fit for domestic, industrial and recreational purposes.
Evolution of Sleep
Sleep is very ancient. In the electroencephalographic sense we share it with all the primates and almost all the other mammals and birds: it may extend back as far as the reptiles.
There is some evidence that the two types of sleep, dreaming and dreamless, depend on the life-style. of the animal, and that predators are statistically much more likely to dream than prey, which are in turn much more likely to experience dreamless sleep. In dream sleep, the animal is powerfully immobilized and remarkably unresponsive to external stimuli.
Dreamless sleep is much shallower, and we have all witnessed cats or dogs cocking their ears to a sound when apparently fast asleep. The fact that deep dream sleep is rare among prey today seemsclearly to be a product of natural selection, and it makes sense that today, when sleep is highly evolved, the stupid animals are less frequently immobilized by deep sleep than the smart ones. But why should they sleep deeply at all?
Why should a state of such deep immobilization ever have evolved? Perhaps one useful hint about the original function of sleep is to be found in the fact that dolphins and whales and aquatic mammals in general seem to sleep very little. There is, by and large, no place to hide in the ocean.
Could it be that, rather than increasing an animal's vulnerability, the function of sleep is to decrease it? Wilse Webb of the University of Florida and Ray Meddis of London University have suggested this to be the case. It is conceivable that animals who are too stupid to be quiet on their own initiative are, during periods of high risk, immobilized by the implacable arm of sleep. The point seems particularly clear for the young of predatory animals. This is an interesting notion and probably at least partly true.
Almost all the mammals and birds do sleep.
A.Right
B.Wrong
C.Not mentioned
Sleep is very ancient. In the electroencephalographic(脑电图仪的)sense we share it with all the primates(灵长类动物)and almost all the other mammals and birds: it may extend back as far as the reptiles(爬行动物).
There is some evidence that the two types of sleep, dreaming and dreamless, depend on the life style. of the animal, and that predators(食肉动物)are statistically much more likely to dream than prey, which are in turn much more likely to experience dreamless sleep. In dream sleep, the animal is powerfully immobilized(使固定不动)and remarkably unresponsive to external stimuli. Dreamless sleep is much shallower, and we have all witnessed cats or dogs cocking their ears to a sound when apparently fast asleep. The fact that deep dream sleep is rare among prey today seems clearly to be a product of natural selection, and it makes sense that today, when sleep is highly evolved, the stupid animals are less frequently immobilized by deep sleep than the smart ones. But why should they sleep deeply at all? Why should a state of such deep immobilization ever have evolved?
Perhaps one useful hint about the original function of sleep is to be found in the fact that dolphins and whales and aquatic mammals in general seem to sleep very little. There is, by and large, no place to hide in the ocean. Could it be that, rather than increasing an animal's vulnerability, Ray Meddis of London University has suggested this to be the case. It is conceivable that animals that are too stupid to be quite on their own initiative are, during periods of high risk, immobilized by the implacable arm of sleep. The point seems particularly clear for the young of predatory animals. This is an interesting notion and probably at least partly true.
Which of the following might be the best title for this passage?
A.Evolution of Sleep.
B.Two Types of Sleep.
C.The Original Function of Sleep.
D.Animals and Sleep.
What potential remedies exist for the acid rain 【C6】______? The experts disagree. Some say new environmental laws should be 【C7】______ to control the emission of pollutants in the atmosphere. Some say that if we had known how serious acid rain was, we would have planned 【C8】______ to prevent it. 【C9】______, all agree that if the consumption of fossil fuel were reduced, we would have less of a problem. Another 【C10】______ is that special scrubbers could be installed in smokestacks to remove a good 【C11】______ of the pollutants before they get into the atmosphere. Other ideas even include breeding more 【C12】______ fish. And research suggests that spreading lime into lakes may be effective in 【C13】______ acidity. In conclusion, it is clear that if we truly want to reduce the impact of acid rain, a 【C14】______ of remedies and international cooperation must be explored. It is a sad fact that acid rain probably could have been avoided if we 【C15】______ what we know now.
【C1】______
A.Likewise
B.Besides
C.Thus
D.Otherwise
Fishes
The term fish is applied to a variety of cold-blooded aquatic vertebrates of several evolutionary lines. Fish share certain features with other vertebrates. These features are gill slits (鳃裂) at some point in the life cycle, a notochord (脊索), or skeletal supporting rod, a dorsal hollow nerve cord, and a tail.
The study of fishes, the science of ichthyology (鱼类学), is of broad importance. There are many reasons why fishes are of interest to humans; the most important is their relationship with and dependence on the environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world's food supply. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean.
Another practical reason for studying fishes is their use in disease control. As predators on mosquito larvae, they help curb malaria and other mosquito borne diseases. Fishes are valuable laboratory animals in many aspects of medical and biological research. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. Fishes have been especially important in the study of animal behaviour where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates.
There are aesthetic and recreational reasons for an interest in fishes. Millions of people keep live fishes in home aquariums for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. To many, aquarium fishes provide a personal challenge, allowing them to test their ability to keep a small section of the natural environment in their homes. Sportfishing is another way of enjoying the natural environment, also indulged in by millions of people every year. Interest in aquarium fishes and sportfishing support multimillion dollar industries throughout the world.
Fishes have been in existence for more than 450,000,000 years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes, for when fishes colonized the land habitat they became tetrapod (四足的) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform. to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration, some for the purpose of camouflage, others for the enhancement of behavioral signals.
Fishes range in adult length from less than 10 millimetres to more than 20 metres and in weight from about 1.5 grams to many thousands of kilogr
A.Y
B.N
C.NG
Approximately 20 percent of the lakes in Scandinavia are without fish. Moreover, in Nova Scotia the【23】salmon industry may be threatened by the decrease of salmon in rivers and streams. The impact is also【24】in the waters of Ontario and Quebec, where fish populations are【25】the decline.
What potential remedies exist for the acid rain【26】? The experts disagree. Some say new environmental laws should be【27】to control the emission of pollutants in the atmosphere. Some say that if we had known how serious acid rain was, we would have planned【28】to prevent it.【29】, all agree that if the consumption of fossil fuel were reduced, we would have less of a problem. Another【30】is that special scrubbers could be installed in smokestacks to remove a good【31】of the pollutants before they get into the atmosphere. Other ideas even include breeding more【32】fish. And research suggests that spreading lime into lakes may be effective in【33】acidity. In conclusion, it is clear that if we truly want to reduce the impact of acid rain, a【34】of remedies and international cooperation must be explored. It is a sad fact that acid rain probably could have been avoided if we【35】what we know now.
(21)
A.Likewise
B.Besides
C.Thus
D.Otherwise
SECTION B PASSAGES
Directions: In this section, you will hear several passages. Listen to the passages carefully and then answer the questions that follow.
听力原文: Sleep is very ancient. In the electroencephalographic sense we share it with all the primates and almost all the other mammals and birds: it may extend back as far as the reptiles.
There is some evidence that the two types of sleep, dreaming and dreamless, depend on the life-style. of the animal, and that predators are statistically much more likely to dream than prey, which are in turn much more likely to experience dreamless sleep. In dream sleep, the animal is powerfully immobilized and remarkably unresponsive to external stimuli. Dreamless sleep is much shallower, and we have all witnessed cats or dogs cocking their ears to a sound when apparently fast asleep. The fact that deep dream sleep is rare among prey today seems clearly to be a product of natural selection, and it makes sense that today, when sleep is highly evolved, the stupid animals are less frequently immobilized by deep sleep than the smart ones. But why should they sleep deeply at all? Why should a state of such deep immobilization ever have evolved? Perhaps one useful hint about the original function of sleep is to be found in the fact that dolphins and whales and aquatic mammals in general seem to sleep very little. There is, by and large, no place to hide in the ocean. Could it be that, rather than increasing an animal's vulnerability, the function of sleep is to decrease it? Wilse Webb of the University of Florida and Ray Meddis of London University have suggested this to be the case. It is conceivable that animals who are too stupid to be quiet on their own initiative are, during periods of high risk, immobilized by the implacable arm of sleep. The point seems particularly clear for the young of predatory animals. This is an interesting notion and probably at least partly true.
What is the passage mainly concerned about?
A.The difference between dream and dreamless sleep of human beings.
B.Why animals with distinctive life style. sleep differently.
C.Deep dream sleep of predators.
D.Stupid animals and smart animals.
The hydrosphere has strange characteristics because water has properties unlike those of any other liquid. One anomaly is that water upon freezing expands by about 9 percent, whereas most liquids contract on cooling. For this reason, ice floats on water bodies instead of sinking to the bottom. If the ice sank, the hydrosphere would soon be frozen solidly, except for a thin layer of surface melt water during the summer season. Thus, all aquatic life would be destroyed and the interchange of warm and cold currents, which moderates climate, would be notably absent.
Another outstanding characteristic of water is that it has a heat capacity which is the highest of all liquids and solids except ammonia. This characteristic enables the oceans to absorb ard store vast quantities of heat, thereby often preventing climatic extremes. In addition, water dissolves more substances than any other liquid. It is this characteristic which helps make oceans a great storehouse for minerals which have been washed down from the continents. In several areas of the world these minerals are being commercially exploited. Solar evaporation of salt is widely practiced, potash is extracted from the Dead Sea, and Magnesium is produced from seawater along the American Gulf Coast.
A characteristic of water NOT mentioned in this passage is that water ______.
A.expands on freezing
B.is a great solvent
C.is like ammonia
D.has a very high heat capacity
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