求一片英语短文的意思?CANyourememberamorningwhenyou’vewokenuptotheringofyouralarmclockandwishedyoucouldstayinbed?Youhaven’tsleptwell,youreyesareblearyandyourhairisamess.Worse,youcan’tstopyawning.Yaw

　　求一片英语短文的意思?

　　CANyourememberamorningwhenyou’vewokenuptotheringofyouralarmclockandwishedyoucouldstayinbed?Youhaven’tsleptwell,youreyesareblearyandyourhairisamess.Worse,youcan’tstopyawning.Yawningisuniversaltohumansandmanyanimals.Cats,dogsandfishyawnjustlikehumansdo!Yawningisaninvoluntary(无意识的)actionduringwhichyouopenyourmouthandbreathedeeply.Theaveragedurationofayawnisabout6seconds.Thepurposeandcauseofyawningarestillamystery.Scientistsarenotsurewhatcausesayawn.Peopleyawnwhentheyaretiredorbored,buttheyalsoyawnwhentheyaren’t.Therearemanyideasexplainingwhyweyawn.Oneideaisthatyawningisawayforthebodytobecomemorealertbytakinginmoreoxygen.Ayawnincreasestheheartrate,forcescarbondioxideoutofthelungs(肺)andbloodstream,andbringsoxygentothebrain.Butonestudyshowedthatvolunteersgivenalotofoxygendidnotyawnanylessthanbefore,whilethosegivenalotofcarbondioxidedidnotyawnmore.Anotherideaisthatearlyhumansusedyawningasaformofcommunication.Ifonedecideditwastimetosleep,theywouldtelltheothersbyyawningandtheywoulddoitinreturntoshowtheyagreed.Athirdexplanationcomesfrompsychology(心理学)professorGordonGallupofUniversityatAlbanyinNewYork.Hesaidthataspeopleyawn,theycoolofftheirbrains.“Brainsarelikecomputers,”hesaid.“Theyonlyoperateefficiently(有效率地)andeffectivelywhenthey’recool.”Manythingsconnectedtoyawning,likebeingtired,makethebrainhot,andyawningcanreducetheheat,hesaid.Scientistshavesentpeopleintospace,buttherearelotsofseemingly(表面上)simplethings,suchaswhyweyawn,orhiccup,thattheycannotfigureout.Nexttimeyouareinclassinthemorning,letoutabigyawnandwatchtoseehowmanyofyourclassmatesyawninresponse!