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问题 选择题

下列各组中的反应，属于同一反应类型的是      

A．由溴丙烷水解制丙醇，由丙烯与水反应制丙醇

B．由甲苯硝化制对硝基甲苯，由甲苯氧化制苯甲酸

C．由氯乙烷制乙烯，由丙烯与溴反应制1,2­二溴丙烷

D．由乙酸和乙醇制乙酸乙酯，由苯甲酸乙酯水解制苯甲酸和乙醇

答案

答案：D

题目分析：A．由溴丙烷水解制丙醇，发生的是取代反应；由丙烯与水反应制丙醇发生的是加成反应，反应类型不同，错误；B．由甲苯硝化制对硝基甲苯发生的是取代反应，由甲苯氧化制苯甲酸发生的是氧化反应，错误；C．由氯乙烷制乙烯发生的是消去反应，由丙烯与溴反应制1,2­二溴丙烷发生的是加成反应，反应类型不同，错误；D．由乙酸和乙醇制乙酸乙酯，发生的是取代反应；由苯甲酸乙酯水解制苯甲酸和乙醇发生的是取代反应，反应类型相同，正确。

多项选择题

酚试剂法是利用蛋白质下列何种氨基酸残基还原磷钨酸—磷钼酸试剂起蓝色反应的原理进行蛋白质定量（ ）

A．色氨酸

B．酪氨酸

C．谷氨酸

D．苯丙氨酸

E．赖氨酸

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问答题

Exercise, everyone advises! But immediately, when you try, you run into trouble. (46)There is so much contradictory, sometimes incorrect advice about exercising that you become confused. Test yourself on the following true false quiz. It will tell you what you need to know.
1. The best way to reduce the mid-section is to do abdominal exercise.
False. Many people believe that when specific muscles are exercised, the fatty tissues in the immediate area are "burned up." (47)The truth-is that exercise burns fat from all over the body and not from one specific area, regardless of the type of exercise. Of course, if you reduce the fat throughout your body, you will certainly see results around your waistline too!
2. To maintain an adequate level of physical fitness, you need to exercise only twice a week.
False. Studies conducted by NASA, the National Aeronautics and Space Administration, show that unexercised muscles lose their strength very quickly. After 48 to 72 hours, you must use the muscles again to reestablish the good physical effect. And what does that mean to you (48) NASA scientists concluded that while daily exercise is most beneficial, three alternating days each week will maintain an adequate level of physical fitness.
3. To lose weight you should always "work up a good sweat" when exercising.
False. Sweating only lowers body temperature to prevent overheating; it does not help you reduce weight. You may weigh less immediately after a workout, but this is due to water loss. Once you replace the liquid, you replace the weight.
4. If your breathing doesn’t return to normal within minutes after you finish exercising, you’ve exercised too much.
True. Five minutes or so after exercising, your breathing should be normal, your heart shouldn’t be pounding, and you shouldn’t be exhausted. (49) Beneficial exercise is not overly difficult, unpleasant, and exhausting; it is moderate, enjoyable, and refreshing.
5. Walking is one of the best exercises.
True. Walking helps circulation of blood throughout the body, and thus has a direct effect or your overall feeling of health.
6. The minimum amount of time you should spend exercising in a day is 20 minutes.
True. There are more than 400 muscles that attach to your skeleton. (50) A good exercise routine should contract and stretch all these muscles, and this simply cannot be done with four or five exercises in five to ten minutes. From experience, I’ve found that about 20 minutes is the minimum amount of time needed for an adequate workout.
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