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If we view a science as a body of systematized knowledge, then chemistry is usually called a natural science because it (26) knowledge of the natural world. At times we may wonder (27) there is no complete system (28) all of chemistry fits perfectly. Gaps in the present system, however, show that chemistry is still a(n) (29) subject and that we (30) all of its facts, laws, and theories. (31) , chemistry as a science is very much (32) us today, and its future holds the bright promise (33) much more to come. Man’s knowledge about himself and nature has grown into (34) sciences. The growth of the separate sciences has been more developmental than intentional. The separation of the natural sciences into physical and biological sciences, and physical sciences into physics and chemistry, happily (35) a larger body of knowledge into more manageable parts. At the same time we should remember that the concepts, techniques, and applications of the various sciences are interdependent and not exclusively a part of one science or (36) . In this (37) , chemistry is a key science among the natural sciences because everyone, (38) the area of natural science he wishes to pursue, needs at least an introduction to the principles and simpler applications of chemistry as a foundation for his specialty. Chemistry deals with the (39) of matter, changes in matter, the laws and principles (40) these changes, and the concepts and theories that interpret them.
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证券投资是指投资者(法人或自然人)购买股票、债券、基金券等有价证券以及这些有价证券的衍生品，以获取红利、利息及资本利得的投资行为和投资过程，是间接投资的重要形式。( )
M: Now, Miss Christina, I see that you are quite a heavy smoker. You told me you smoke about thirty a day. Well, my advice is quite simple: stop smoking. You know that cigarettes cause cancer and heart disease. Have you tried to give upW: Yes, lots of times. But I just find it impossible to stop.M: Well, in that case, let me suggest five things which you can do. First of all, if you smoke strong cigarettes, you should change to milder ones. But that won’t help you if you smoke more. So, secondly, don’t smoke as many cigarettes. Try to cut down by one or two every day. OK The next three points are to do with how you smoke. The most important is this: don’t breathe the smoke in. It’s when you breathe in the smoke that you do most damage to your health. Next, don’t keep the cigarette in your mouth all the time. Pat it in an ashtray when you are not smoking it. And finally, don’t smoke all the cigarette. The end of a cigarette is very dangerous to your health. So put the cigarette out after you have smoke half of it. All right What is the most important suggestion given by the man（）
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