Exercise is good for you， but most people really know very little about how to exercise properly. 1 when you try， you can runsintostrouble. Many people 2 that when specific muscles are exercised， the fat in the neighbouring area is“ 3 up”。Yet the 4 is that exercise burns fat from all over 5 . Studies show muscles which are not 6 lose their strength very quickly.To regain it needs 48 to 72 hours and exercise every other day will 7 a normal level of physical strength. To 8 weight you should always“work up a good sweat”when exercising. 9 sweating only 10 body temperature to prevent over heating.This is 11 water loss. 12 You replace the liquid， you replace the 13 . Walking is the best and easy-to-do exercise.It helps the circulation of blood 14 the body， and has a direct 15 on your overall feeling of health.Experience says that 20 minutes 16 17 is minimun amount. 18 your breathing doesn t return to normal state within minutes after you finish 19 ， you ve done 20 . 1.A.While B.When C.As D.So 2.A.understand B.believe C.hope D.know 3.A.built B.burned C.piled D.grown 4.A.reply B.possiblility C.truth D.reason 5.A.arm B.leg C.stomach D.body 6.A.exercised B.examined C.protected D.cured 7.A.lose B.raise C.burn D.keep 8.A.lose B.gain C.keep D.burn 9.A.Certainly B.No C.Fortunately D.Probably 10.A.raises B.reduces C.destroys D.keeps up 11.A.how B.why C.nothing but D.more than 12.A.While B.Once C.As D.Whenever