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单选题______A bestB justiceC fairD worst
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问答题Pollution and Ecocrisis The problem of pollution is also of great social concern. Continued population increase, accompanied by a rise in the level of living standards, not only threatens to exhaust American resources but pollutes the environment to such an extent that production in the thickly settled area is impossible without damaging the health of the local residents. Smog, once an urban annoyance, is now recognized as a health risk, and the automobile has been pinpointed as the principal culprit. Heavy industries have been blamed for river, soil, air, noise and visual pollutions. DDT and other chemical remedies have been doing more ecological harm than the good that they may have brought along. Several decades ago, Americans dumped raw sewage into rivers and many industrial plants are now still dumping chemical pollutants into lakes, rivers and oceans. Oceans used to be and are still being considered to be a reserve of seafood. Today, after the oceans have become the home of all pollutants, this use of the oceans is being reduced at an alarming rate. The worst pollution threat is concentrated in and near large cities. There the people-made pollutants increasingly surpass the ability of air and water to dilute (冲淡；稀释) the contaminants (污染物) to safe levels. The natural ecological cycle depends on plants, which absorb some pollutants and release oxygen to the air. But near large cities, natural vegetation becomes scarce, and introduced trees, ornamental shrubs and gardens are far from adequate in absorbing motor vehicle and industrial air pollutants. Finally, some pollutants, most notably atomic waste, may continue to contaminate air, land, and water for thousands of years. Therefore, ecocrisis—ecocatastrophe or ecocide—has been for some time one of the major concerns of not only the ecoactivists and environmentalists, but of many scientists of other fields and the government authorities of many countries as well. Last but not least, there is the question of whether the people will eventually be able to solve all these problems. The American continent is a wealthy land inhabited by many able and well- educated people. There today, people have originated a life-style which is known to the world as being characteristic of a society of consumption—a life-style based on the prodigal (挥霍浪费的) use of material goods. They are using up many times their share of the earth’s resources at a rate unparalleled in history. And I am sorry to say that this life-style of American has been copied by the people of many developed countries, leading to the greatest problem of the modem world as a whole. So I must ask: Are the Americans apt enough to cooperate with other peoples to prevent over-population, resource exhaustion, the catastrophe of pollution and the wanton waste of wealth — problems which are basic to the solution of many outstanding economic, social and political problems? Only time will tell.
问答题The Truth about Genetically Modified Food At almost every public lecture I give, someone asks me my opinion on genetic modification—whatever be the topic of the lecture. Genetic modification (GM) has the power to save lives through its use in medicine, such as the production of insulin for diabetics or the treatment of genetic disorders. The current outcry comes when it is used to produce food. Some of these public concerns reflect real problems, but others are fuelled by misinformation and overdramatisation. There is nothing new about crop modification; plant breeders have been doing it since agriculture began. The wonderful range of apples or potatoes we now enjoy is the result of crossing different varieties. Cabbages, Brussels sprouts, cauliflower, kohlrabi, kale and broccoli all originated from one botanical species. Modern molecular biology has enabled us to go much further. We can now isolate the gene for a particular characteristic of an organism and transfer it to another species. It is this practice of transforming a plant with alien genes—perhaps from an animal or bacterium—that is causing all the controversy. There are three main concerns. Scientists can now take a gene for resistance to a particular herbicide and transfer it to a crop: when these plants are sprayed with weed-killer, the weeds are destroyed while the crop is unharmed. A prime concern is the harmful effect this could have on the biodiversity of farmland, where so many insects, birds and other animals depend upon “weed” species. Another fear is that alien genes from a GM plant could escape into a wild population of a related species. Since plants are fertilized by pollen that is carried through their, often for great distances, this is entirely possible. A wild species modified in this way with pesticide resistance could become a “super-weed”, while a species that becomes unnaturally resistant to animals that feed on it could disrupt the food chain. The third worry concerns a proposal to produce seeds for cereals that cannot germinate to produce next year’s seeds. This “terminator technology” would be of obvious advantage to seed companies, since farms would be forced to buy new weed annually. But the same technology could be devastating to some farmers in the developing world who depend upon saving some seeds for next year’s crop. Fortunately this technology is not yet in use and there has been strong pressure to abandon it. I would not hesitate to eat a GM vegetable—it is most unlikely that the current modifications are harmful to the consumer, despite what we read in the press. However, the introduction of animal genes into food plants presents considerable ethical difficulties to vegetarinsarians and member of religious that forbid the eating of certain animals. This is one of the reasons people are demanding that tall genetically modified food products be clearly labeled. The public have a fight to know what they are eating and a fight to choose. I believe that in my own nation GM is well regulated, but this cannot be said for some other countries. One of the problems is that at the moment this technology is commercially motivated. Because the compositions developing GM food want to introduce it as quickly as possible, in my opinion, it is being rushed into without adequate research or precautions. Genetic’ modification is here to stay, and there is no doubt it will save lives. But ,like so many other scientific discoveries, such as splitting the atom, it can be seriously misused. Instead of condemning the technique, we, should ensure it is used wisely. We need to evaluate each application carefully, from environmental and ethical standpoints, and we must urge governments and companies to use it for good rather than for greed.
单选题______A near B under C on D above
单选题______A brightnessB foreseeingC foresightD prediction
单选题______A SymptomsB SignalsC Highlights D Incidences
单选题______A worseB as goodC betterD best
