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问题 多项选择题

有关对红霉素结构修饰的叙述，正确的有

A．将红霉素修饰成酯，得到琥乙红霉素，在胃酸中稳定，无苦味，进入体内释放出红霉素发挥药效

B．将红霉素6位羟基甲基化，得到克拉霉素，增强了对胃酸的稳定性，活性提高

C．将红霉素9位引入肟基，得到罗红霉素，稳定性增强，脂溶性提高，肺组织浓度高

D．将红霉素与乳糖醛酸成盐，水溶性提高，可供注射

E．将红霉素经重排扩环、还原、甲基化反应后，得到阿奇霉素，碱性提高，对革兰阴性菌作用增强

答案

参考答案：A,B,C,D,E

单项选择题

“昧真中之有假，执似是而实非”（《病家两要说》）中的主语是（）

A.当事人 

B.局外人 

C.常医 

D.真医
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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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