听音频 回答题 Elephants have a complex social structure

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Elephants have a complex social structure and they live in26societies. The basic family unit is formed of small groups of adult females， who are 27 each other， and their young of both sexes. Now the females remain in their families for life， they"re highly social， but male elephants leave their families at about fourteen years of age. They travel alone or stay together in small，28 groups with other males，29 joining a family on a temporary basis. When males are ready to mate they wander widely， searching for 30 females. The family unit， on the other hand， often contains three generations， and it can remain stable for decades， or even centuries. Then each family 31 between one and five other families， probably consisting of their more distant relatives. Scientists call these groups of families "bond groups"， and bond groups belong，32， to even larger groups， called clans. And like other social animals they have to be able to communicate. But what baffled early33was their ability to communicate over long distances. So they set about researching this question. After years of observation and study， our understanding of elephant communication has increased considerably in recent years. However， even with the use of radio tracking collars， it"s technically difficult to 34 the functions of long-range communication. So although scientists are aware that elephants may know the whereabouts， and possibly the activities of other elephants that are several miles away，there may be a lot of subtle， long-range35which are still not evident.
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