TalesofthesupernaturalarecommoninallpartsofBritain.Inparticular,therewas(andperhapsstillis)abeliefinfairies.Notallofthese51arethefriendly,people-lovingcharac-tersthatappearinDisneyfilms,andinsomefolktalestheyare52andcausemuchhumansuf-fering.ThisistrueinthetalesabouttheChangeling.Thesetellthestoryofamotherwhoseba-bygrows53andpaleandhaschangedsomuchthatitisalmost54totheparents.Itwasthen55thatthefairieshadcomeandstolenthebabyawayand56thehumanbabywithafairyChangeling.Thereweremanywaystopreventthisfromhappening:hangingaknifeoverthebaby'sheadwhilehesleptorcoveringhimwithsomeofhisfather'sclotheswerejusttwooftherecommended57.However,hopewasnotlostevenifthebabyhadbeen58.Inthosecasestherewasoftenawaytogetthe59babyback.Youcould60theChangelingonthefire--thenitwouldriseupthechimney,andyouwouldhearthesoundoffairies'laughterandsoonaf-teryouwouldfindyourownchildsafeandsoundnearby. 阅读以上短文，回答171-180题。 第51题答案是__________
A.babies B.fairies C.believers D.supermen正确答案B
