The temperature of your body should be always just the same, no matter whether the weather is trot or colD、That is why the doctor uses his thermometer when you are sick. When you are well,your temperature is ninety-eight and six tenths degrees. If he finds it (51) than that,it is a sure sign that something is wrong. The body keeps the same temperature all the time,because it balances (平衡) the heat it produces and (52) off. It is always burning up food and producing heat. It can produce heat faster when it needs to or give off heat faster when it becomes too warm. Let’s see (53) this happens. The heat of your body is given off chiefly through the skin. When you are (54) ,your skin is tight and shows "goose flesh". When you get chilly (寒冷的),you must dance around to keep warm or (55) you will shiver (颤抖). (56) your muscles begin to work,burn up fuel,and produce more heat. It is not (57) to shiver,so you usually prefer warming up by exercise, or put (58) more clothes to keep heat in. When you are warm,the skin is loose and soft. It is so supplied (59) blood that heat is given off rapidly. If you get too hot,you begin to sweat,and (60) body heat is used in evaporating (蒸发) the moisture (潮湿) from your skin. You wear less clothing, too, in warm (61) or in a warm room,so that warmth can be given off freely. You feel you don’t (62) exercising because your body is warm (63) ,and the extra heat produced by exercise makes you uncomfortable. You can see from this why you (64) differently in different kinds of weather. In summer,when it is warm,you feel tired and lazy. You do not care to work or play,but enjoy lying and doing nothing. When you get out of doors in winter,the cold air makes you feel (65) . You want to run and play. A、off B、away C、up D、on
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