题目内容：
听音频，回答题 Elephantshaveacomplexsocialstructureandtheylivein26societies.Thebasicfamilyunitisformedofsmallgroupsofadultfemales,whoare27eachother,andtheiryoungofbothsexes.Nowthefemalesremainintheirfamiliesforlife,they'rehighlysocial,butmaleelephantsleavetheirfamiliesataboutfourteenyearsofage.Theytravelaloneorstaytogetherinsmall,28groupswithothermales,29joiningafamilyonatemporarybasis.Whenmalesarereadytomatetheywanderwidely,searchingfor30females.Thefamilyunit,ontheotherhand,oftencontainsthreegenerations,anditcanremainstablefordecades,orevencenturies.Theneachfamily31betweenoneandfiveotherfamilies,probablyconsistingoftheirmoredistantrelatives.Scientistscallthesegroupsoffamilies"bondgroups",andbondgroupsbelong,32,toevenlargergroups,calledclans.Andlikeothersocialanimalstheyhavetobeabletocommunicate.Butwhatbaffledearly33wastheirabilitytocommunicateoverlongdistances.Sotheysetaboutresearchingthisquestion.Afteryearsofobservationandstudy,ourunderstandingofelephantcommunicationhasincreasedconsiderablyinrecentyears.However,evenwiththeuseofradiotrackingcollars,it'stechnicallydifficultto34thefunctionsoflong-rangecommunication.Soalthoughscientistsareawarethatelephantsmayknowthewhereabouts,andpossiblytheactivitiesofotherelephantsthatareseveralmilesaway,theremaybealotofsubtle,long-range35whicharestillnotevident.
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