北京高考英语试卷真题答案解析及点评（WORD文字版）（5）
更新时间：2018-07-29 16:02作者：才子老师
parentobjectdoesn’tlookverydifferentfromthesurroundingairorwater.Youdon’tseeit----youseethethingsbehindit.
Tobecometransparent,ananimalneedstokeepitsbodyfromabsorbingorscatteringlight.Livingmaterialscanstoplightbecausetheycontainpigments(色素)thatabsorbspecificcolorsoflight.Butatransparentanimaldoesn’thavepigments,soitstissueswon’tabsorblight.AccordingtoJohnsen,avoidingabsorptionisactuallyeasy.TherealchallengeisPventinglightfromscattering.
Animalsarebuiltofmanydifferentmaterials----skin,fat,andmore----andlightmovesthrougheachatadifferentspeed.Everytimelightmovesintoamaterialwithanewspeed,itbendsandscatters.Transparentanimalsusedifferenttrickstofightscattering.Someanimalsaresimplyverysmallorextremelyflat.Withoutmuchtissuetoscatterlight,itiseasiertobesee—through.Othersbuildalarge,clearmassofnon-livingjelly-lie(果冻状的)materialandsPadthemselvesoverit.
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