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夏天买棒冰时，某同学发现，售货员刚从冰箱里拿出棒冰，硬邦邦的棒冰上粘着白花花的“粉”，一剥去包装纸，棒冰就“冒烟”；他把这支棒冰放进茶杯里，不一会儿，茶杯外壁又会“出汗”，请你帮助他解释这三个现象吗？

答案

答：“粉”是空气中水蒸气遇冷的棒冰凝华而成的小冰粒；

“冒烟”是空气中水蒸气遇冷的棒冰液化成的小水珠；

“出汗”是空气中水蒸气遇冷（温度较低）的茶杯外壁液化成的小水珠．

填空题

砂岩束缚水饱和度与（）和（）有关，其变化范围（）。
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填空题

41.

Two types of stress:


There are basically two types of stress placed on human beings--physical and mental.
42.

Effects of stress--physical or emotional:


Whether physical or emotional in origin, stress causes the body to react in the same way.
43.

Guilty--useful, though most harmful:


Probably the most harmful of all the stresses is guilt.
44.

Instances no need to feel guilty:


However, many of us as children learned rules that we no longer need.

No one is perfect:


Guilt and the worry that often accompanies this major stress are difficult to eradicate, but people subject to excessive guilt feelings should realize, as simple as it sounds, that no one is perfect. People cannot always be cheerful and helpful to every one they meet. Another good lesson is that mistakes should be forgotten, not lingered over and brought out to examine periodically.
45.

Life with a little stress--significant:


A life without stress, such as retirement with nothing to do, would be boring.
[A] Fat adults should no longer feel guilty about leaving a little food on the plate, a successful businessman need not feel guilty about spending a little too much money on a vacation, nor should he feel guilty that he can combine a business trip to the West Coast with some swimming and golf at an ocean resort. But many people do feel guilty over such apparently innocent actions. Excessive guilt can sour all of life and make life not worth living; it can also cause self-hatred as well as other fears and anxieties that cause all life’s successes to be bittersweet, at best.
[B] Stress from physical activity, if not carried too far, is actually beneficial. Exercise relaxes you and may help forget about mental and emotional stress. But mental stress is almost always bad for you. If mental stress is unrelieved, it can actually cause diseases such as ulcers, migraine headaches, heart problems, or mental illness.
[C] Just as we need a little guilt--to keep us correct and a little worry--to make us plan ahead--we need a little stress to stay interested in life. But when stress begins to bother you, you might as well change your routine. Take your mind off your worries with some physical activity; you may discover a solution you have overlooked before.
[D] Stress is a natural part of everyday life and there is no way to avoid it. In fact, it is not the bad thing it is often supposed to be. A certain amount of stress is vital to provide motivation and give purpose to life. It is only when the stress gets out of control that it can lead to poor performance and ill health.
[E] Some people are not afraid of stress, and such characters are obviously prime material for managerial responsibilities, others lose heart at the first signs of unusual difficulties.
[F] In the first stage, your body prepares to meet the stress. The heartbeat and respiration rates increase, and the pupils of the eyes dilate; the blood sugar level increases, and the rate of perspiration speeds up, while digestion slows down as blood and muscular activity is diverted elsewhere. In the second stage, your body returns to normal and repairs any damage caused by the stressful situation. However, if stress continues, the body cannot repair itself, and the final stage, exhaustion, then begins. If this stage continues, if for example you are frustrated by your work and continue to be frustrated for a long time, physical or emotional damage will occur. These stages of stress reaction are always the same, whether the stress is caused by a cross-country run, a first date, buying a house, or narrowly missing an automobile accident.
[G] This common emotion is useful to have when it helps us to realize that we have, in fact, committed some error, violated our own rules or social rules. If we did not feel guilty, we would never do anything except the things that brought us immediate pleasure-- we’d never obey the law, work, exercise, or even study in school, unless we wanted to do so in the first place. As a person’s conscience develops, guilt feelings become inevitable; guilt is the sorrow we experience when we know we have done something incorrect.
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