题目内容：
根据以下材料，回答题Ifyouarewritingorstudying,itmakesverymuchdifferencewherethelightcomesfrom.Peoplewhousebooksandpenseverydayhavetobeespeciallycarefulabouttheway.thelightshineson
theirwork.Everyhousegetsitslighteitherfromdaylightthroughthewindows--whichisthebesttouse--orfromlampsorelectricity;butwhicheverkindoflightitis,thewayitshinestowardourbookorworkisamatterofgreatimportancetotheeyes.Takeabook,sitwithyourbacktowardthewindow,
andtrytoread.Yourshadow(影子)fallsalloverthepageandmakesitalmostasbadforyoureyesasifyouwereinadarkroom.
Nowturnaroundandfacethewindow.Thepageisintheshadowagain,whilethebrightlightisinyoureyes.Trysittingwithyourrightsidetowardthewindow.Thisisverywellforreading,butifyou
werewriting,theshadowofyourhandwouldfallacrossthepageandbother(打搅)youalittle.Thereisjustoneotherway:sitwithyourleftsidetothewindow.Noweverythingisperfectformreadingandforwriting,too.
Whateverkindoflightisintheroom,theruleabouttherighttositisalwaysthesame.
Whichofthefollowingistrue? A．Howthelightshinesonourworkisofmuchimportance.
B．Thewaythelightshinesonyourworkmakesnodifference.
C．Weneedn'tcareaboutwherethelightcomesfrom.
D．Peoplecanwriteorstudyunderalightthatcomesfromanydirection.
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答案解析：