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问题 选择题

The harm the modern farming methods have done________the countryside is considerable. [ ]

A. on  

B. to

C. at  

D. for

答案

答案：B

单项选择题

心肌细胞内的Ca2+贮存在（）。

A.肌浆内

B.肌浆网内

C.线粒体内

D.横小管内

E.心肌细胞外
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问答题

People today all over the world are beginning to hear and learn more and more about the problem of pollution. (46) Pollution is caused by either the release by man of completely new and often artificial substances into the environment, or by releasing greatly increased amounts of a natural substance, such as oil from oil tankers into the sea.
(47)The whole industrial process which makes many of the goods and machines we need and use in our daily lives, is bound to create a number of waste products which upset the environmental balance, or the ecological balance as it is also known. (48) Many of these waste products can be prevented or disposed of sensibly, but clearly while more and more new goods are produced and made complex, there will be new, dangerous wastes to be disposed of, for example, the waste products from nuclear power stations.
(49)Whatever its underlying reasons, there is no doubt that much of the pollution caused could be controlled if only companies, individuals and governments would make more efforts. In the home there is an obvious need to control litter and waste. Food comes wrapped up three or four times in packages that all have to be disposed of; drinks are increasingly sold in bottles or tins which cannot be reused. This not only causes a litter problem, but also is a great waste of resources, in terms of glass, metals and paper. Advertising helped this process by persuading many of us not only to buy things we neither want nor need, but also to throw away much of what we do buy. (50)Pollution and waste combine to be a problem every one can help to solve by cutting out unnecessary buying, excess consumption and careless disposal of the products we use in our daily lives.
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