The temperature of your body should be always just the same, no matter whether the weather is hot 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.

　　51　A　taller　　B　better　　C　superior　　D　higher

　　52　A　gives　　B　puts　　C　shows　　D　keeps

　　53　A　how　　B　when　　C　what　　D　why

　　54　A　warm　　B　hot　　C　cool　　D　cold

　　55　A　but　　B　well　　C　so　　D　else

　　56　A　However　　B　While　　C　Then　　D　Therefore

　　57　A　glad　　B　pleasant　　C　surprising　　D　polite

　　58　A　off　　B　away　　C　up　　D　on

　　59　A　by　　B　with　　C　through　　D　of

　　60　A　more　　B　enough　　C　many　　D　little

　　61　A　weather　　B　climate　　C　circumstance　　D　environment

　　62　A　desirable　　B　like　　C　wanting　　D　hate

　　63　A　yet　　B　still　　C　already　　D　too

　　64　A　wear　　B　feel　　C　dress　　D　sweat

　　65　A　lively　B　lovely　C　anxious　　D　depressed

　　参考答案：

　　51 D 52 A 53 A 54 D 55 D 56 C57 B 58 D

　　59 B 60 A 61 A 62 B 63 C 64 B 65 A