Vitamins are organic compounds necessary in small ...

第1题

Vitamins are organic compounds necessary in small amounts in the diet for the normal growt

h and maintenance of life of animals, including man.

They do not provide energy,【21】do they construct or build any part of the body. They are needed for【22】foods into energy and body maintenance. There are thirteen or more of them, and if【23】is missing a deficiency disease becomes【24】.

Vitamins are, similar because they are made of the same elements--usually carbon, hydrogen, oxygen, and【25】nitrogen. They are different【26】their elements are arranged differently, and each vitamin【27】one or more specific functions in the body.

【28】enough vitamins is essential to life, although the body has no nutritional use for【29】vitamins. Many people,【30】, believe in being on the "safe side" and thus take extra vitamins. However, a well-balanced diet will usually meet all the body's vitamin needs.

(36)

A．either

B．so

C．nor

D．never

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第2题

Are organically grown foods the best food choices？ The advantages claimed for such foods o

ver conventionally grown and marketed food products are now being debated. Advocates of organic foods frequently proclaim that such products are safer and more nutritious than others.

The growing interest of consumers in the safety and nutritional quality of the typical North American diet is a welcome development. However, much of this interest has been sparked by sweeping claims that the food supply is unsafe or inadequate in meeting nutritional needs. Although most of these claims are not supported by scientific evidence, the greater number of written material advancing such claims make it difficult for the general public to sep arate fact from fiction. As a result, claims that eating a diet consisting entirely of organically grown foods prevents or cures disease or provides other benefits to health have become widely publicized and form. the basis for folklore.

Almost daily the public is surrounded by claims for "no-aging" diets, new vitamins, and other wonder foods. There are numerous unsubstantiated reports that natural vitamins are superior to synthetic ones, that crops grown with organic fertilizers are nutritionally superior to chose with chemical fertilizers, that untreated grains are better than fumigated grains, and the like.

One thing that most organically grown food products seem to have in common is that they cost more than conventionally grown foods. But in many cases consumers are misled if they believe organic foods can maintain health and provide better nutritional quality than conventionally grown foods. So there is real cause for concern ff consumers, particularly those with limited incomes, distrust the regular food supply and buy only expensive organic foods instead.

The author implies that there is cause for concern if consumers with limit ed incomes buy organic foods instead of conventionally grown foods be cause ______ .

A．organic goods can be more expensive but are often no better than conventionally grown foods

B．many organic foods are actually less nutritious than similar conventionally grown foods

C．conventionally grown foods are more readily available than organic foods

D．too many farmers will stop using conventional methods to grow food crops

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第3题

Increasingly, over the past ten years, people—especially young people—have become aware of

the need to change their eating habits, because much of the food they eat, particularly processed food, is not good for the health. Consequently, there has been a growing interest in natural foods. Foods which do not contain chemical additives(添加剂) and which have not' been affected by chemical fertilizers, widely used in farming today.

(79) Natural foods, for example, are vegetables, fruit and grain which have been grown in soil that is rich in organic (有机的) matter. In simple terms, this means that the soil has been nourished by unused vegetable matter, which provides it with essential vitamins and minerals. This in itself is a natural process compared with the use of chemicals and fertilizers, the main purpose of which is to increase the amount—but not the quality—of foods grown in commercial farming areas.

Natural foods also include animals which have been allowed to feed and move freely in healthy pastures(牧场). Compare this with what happens in the mass production of poultry: there are farms, for example, where thousands of chickens live crowded together in one building and are fed on food which is little better than rubbish. Chickens kept in this way are not only tasteless as food, they also lay eggs which lack important' vitamins.

There are other aspects of healthy eating which are now receiving increasing attention from experts on diet. Take, for example, the question of sugar. This is actually a non-essential food ! Although a natural alternative, such as honey, can be used to sweeten food if it is necessary, we can in fact do without it. It is not that sugar is harmful in itself. But it does seem to be addictive: the quantity we use has grown steadily over the last two centuries and in Britain today each person consumes an average of 200 pounds a year! Yet all it does is to provide us with energy, in the form. of calories. There are no vitamins in it, no minerals and no fiber.

(80) It is significant that nowadays fiber is considered to be an important part of a healthy diet. In white bread, for example, the fiber has been removed. But it is present in unrefined flour and of course in vegetables. It is interesting to note that in countries where the national diet contains large quantifies of unrefined flour and vegetables, certain diseases are comparatively rare. Hence the emphasis is placed on the eating of whole meal bread and more vegetables by modem experts on "healthy eating".

People have become more interested in natural foods because ______.

A．they are more health conscious

B．they want to taste all kinds of foods

C．natural foods are more delicious than processed foods

D．they want to return to nature

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第4题

Increasingly, over the past ten years, people -- especially young people have become aware

of the need to change their eating habits, because much of the food they eat, particularly processed food, is not good for the health. Consequently, there has been a growing interest in natural foods: foods which do not contain chemical additives and which have not been affected by chemical fertilizers, widely used in farming today.

Natural foods, for example, are vegetables, fruit and grain which have been grown in soil that is rich in organic matter. In simple terms, this means that the soil has been nourished by unused vegetable matter, which provides it with essential vitamins and minerals. This in itself is a natural process compared with the use of chemicals and fertilizers, the main purpose of which is to increase the amount-- but not the quality -- of foods grown in commercial farming areas.

Natural foods also include animals which have been allowed to feed and move freely in healthy pastures. Compare this with what happens in the mass production of poultry: there are battery farms, for example, where thousands of chickens live crowded together in one building and are fed on food which is little better than rubbish. Chickens kept in this way are not only tasteless as food; they also produce eggs which lack important vitamins.

There are other aspects of healthy eating which are now receiving increasing attention from experts on diet. It is significant that nowadays fiber is considered to be an important part of a healthy diet. In white bread, for example, the fiber has been removed. But it is presented in unrefined flour and of course in vegetables. It is interesting to note that in countries where the national diet contains large quantities of unrefined flour and vegetables, certain diseases are comparatively rare. Hence emphasis placed on the eating of whole meal bread and more vegetables by modem experts on "healthy eating."

According to this passage, people becoming interested in natural foods because ______.

A．they are getting fired of processed foods

B．they want to change their eating habits

C．a lot of the foods they eat is not healthy

D．food experts recommend them to have natural foods

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第5题

Vitamins are complex ________ that the body requires in very small mounts. A．matte

Vitamins are complex ________ that the body requires in very small mounts.

A．matters

B．materials

C．particles

D．substances

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第6题

A. flour B. milk C. vitamins D. eggs

A.flour

B. milk

C. vitamins

D. eggs

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第7题

The vitamins necessary for a healthy body are normally supplied by a ______ of fruit and g

reen vegetables.

A．variety

B．fraction

C．section

D．series

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第8题

Vitamins do not provide energy, nor do they construct or build any part of the body. They

are needed for ______ foods into energy and body maintenance.

A．transforming

B．transferring

C．altering

D．shifting

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第9题

By "if the fuel isn't there, the spark is useless", the author means______.A．carbohydrates

By "if the fuel isn't there, the spark is useless", the author means______.

A．carbohydrates, protein and fat are enough to sustain a human life

B．vitamins and minerals are virtually of no value

C．carbohydrates, protein and fat are as important as vitamins and minerals

D．without carbohydrates, protein and fat, vitamins and minerals are of no use

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第10题

Organic agriculture is a relatively untapped resource for feeding the Earth's popu

lation，especially inthe face of climate change and other global challenges. That's the conclusion I reached in reviewing40 years of science comparing the long-term prospects of organic and conventional farming.

The review study,"Organic Agriculture in the 21st Century,”is featured as the cover story for theFebruary issue of the journal Nature Plants. It is the first to compare organic and conventional agricultureacross the main goals of sustainability identified by the National Academy of Sciences: productivity,economics，and environment.

Critics have long argued that organic agriculture is inefficient，requiring more land to yield the sameamount of food. It's true that organic farming produces lower yields，averaging 10 to 20 percent less thanconventional. Advocates contend that the environmental advantages of organic agriculture far outweighthe lower yields，and that increasing research and breeding resources for organic systems would reduce theyield gap.Sometimes excluded from these arguments is the fact that we already produce enough food tomore than feed the world's 7.4 billion people but do not provide adequate access to all individuals

In some cases，organic yields can be higher than conventional. For example，in severe droughtconditions，which are expected to increase with climate change in many areas，organic farms can produceas good，if not better，yields because of the higher water-holding capacity of organically farmed soils.

What science does tell us is that mainstream conventional farming systems have provided growingsupplies of food and other products but often at the expense of other sustainability goals.

Conventional agriculture may produce more food，but it often comes at a cost to the environment.Biodiversity loss，environmental degradation，and severe impacts on ecosystem services have not onlyaccompanied conventional farming systems but have often extended well beyond their field boundaries.With organic agriculture，environmental costs tend to be lower and the benefits greater.

Overall，organic farms tend to store more soil carbon，have better soil quality， and reduce soil erosioncompared to their conventional counterparts. Organic agriculture also creates less soil and water pollutionand lower greenhouse gas emissions. And it's more energy-efficient because it doesn't rely on syntheticfertilizers or pesticides.

Organic agriculture is also associated with greater biodiversity of plants，animals，insects andmicroorganisms as well as genetic diversity. Biodiversity increases the services that nature provides andimproves the ability of farming systems to adapt to changing conditions.

Despite lower yields，organic agriculture is more profitable for farmers because consumers are willingto pay more.Higher prices，called price premiums，can be justified as a way to compensate farmers forproviding ecosystem services and avoiding environmental damage or external costs.

51. What do we learn from the conclusion of the author's review study？

A)More resources should be tapped for feeding the world's population.

B)Organic farming may be exploited to solve the global food problem.

C)The long-term prospects of organic farming are yet to be explored.

D) Organic farming is at least as promising as conventional farming.

52. What is the critics' argument against organic farming？

A)It cannot meet the need for food.

B) It cannot increase farm yields.

C )It is not really practical.

D) It is not that productive.

53. What does the author think should be taken into account in arguing about organic farming？

A)Growth in world population.

B)Deterioration in soil fertility.

C) Inequality in food distribution.

D)Advance in farming technology.

54. What does science tell us about conventional farming？

A) It will not be able to meet global food demand.

B)It is not conducive to sustainable development.

C) It will eventually give way to organic farming.

D) It is going mainstream throughout the world.

55. Why does the author think higher prices of organic farm produce are justifiable？

A)They give farmers going organic a big competitive edge.

B)They motivate farmers to upgrade farming technology.

C) Organic farming costs more than conventional farming.

D)Organic farming does long-term good to the ecosystem.

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