()4.Howmuchsleepshouldboysandgirlsofnineyearshaveeverynight?A.EighthoursB.Ninewearereadytoworkandplayagain.Whileweareasleepourbodiesgrowmost.Childrenusuallyneedmoresleep.Wecangetourlessonsbetterandwefeelbette

　　()4.Howmuchsleepshouldboysandgirlsofnineyearshaveeverynight?A.EighthoursB.Nine

　　wearereadytoworkandplayagain.Whileweareasleepourbodiesgrowmost.Childrenusuallyneedmoresleep.Wecangetourlessonsbetterandwefeelbettertoo,whenwehaveplentyofrest.Boysandgirlsneedtenhoursofsleepeverynightwhentheyareeightornineyearsold.Ourbodiesneedlotsofairwhenwesleep.Ifwedonotgetenoughfresh（新鲜的）airwe’llfeeltiredwhenwewap.Whileinbedwemustnotcoverourheads.Ifwedo,ourlungs（肺）willnotgetenoughfreshair.Ifweopenourwindowsatnightwecanhaveplentyoffreshair.Coolairisbetterthenwarmair.Boysandgirlsmustgetenoughsleepiftheywanttogrowandbestrong.