sleepasweknowisimportanttousbecauseithelpsrestoretiredorgansan
根据短文内容,从下框的A~F选项中选出能概括每一段主题的最佳选项.选项中有一项为多余项.
A.Ageneralsleeprule.
B.Theimportanceofsleep.
C.Afunnysleepingexample.
D.Differentlevelsofsleep.
E.Thetimeweneedforsleep.
F.Differentstatesofsleep.
61.
Sleep,asweknow,isimportanttousbecauseithelpsrestoretiredorgansandtissuesinourbody.Buthowmuchsleepdoweactuallyneed?
62.
Formostofus,eighthoursseemstobeabouttherightamount.Yetweknowthatthereareagreatmanypeoplewhogetalongperfectlywithlesssleepandsomewhomayevenneedmore.Agreatdealdependsonthewaywelive.Butagoodgeneralruletofollowistosleepaslongaswehavetoinordertofeelhappyandbeabletoworkatourbestwhenweareawake.
63.
Thereareactuallydifferentlevelsofsleep.Thereisadeepsleepandashallowsleep.Inashallowsleepourbodydoesnotgetthesamekindofrestasitgetsinadeepsleep,sothataftereighthoursofashallowsleepwemaystillfeeltired.Butashortdeepsleepcanbeveryrestful.
64.
AlexandertheGreatwasabletogetadeepsleepwheneverheneededit.Once,duringthenightbeforeanimportantbattle,heremainedawakelongerthananyoneelse.Thenhewrappedhimselfinacloakandlaydownontheearth.Hesleptsodeeplythathisgeneralshadtowakehimthreetimestogivecommandtoattack!
65.
Normallywhenwegotosleep,our“sleepcenter”blocksoffnervessothatbothourbrainandourbodygotosleep.Onepreventsusfromwantingtodoanythingandtheothermakesourinternalorgansandlimbsgotosleep.Butsomeonewillfallasleep(brainsleep)andkeeponmarching,becausehisbodyisnotasleep!
