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  3. [audioFiles]2012q3/audio_ezfm_061_20129[/audioFiles] Most animals have littl

[audioFiles]2012q3/audio_ezfm_061_20129[/audioFiles] Most animals have littl

游客2023-11-13  55
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答案     Most animals have little connection with animals of a different kind,/ unless they hunt them for food./ Sometimes, however, two kinds of animals come together in a partnership/ which does good to both of them./ You may have noticed some birds sitting on the backs of sheep./ This is not because they want a ride,/ but because they find easy food in the parasites on sheep./ The sheep allow the birds to do so/ because they remove the cause of discomfort./ So although they can manage without each other, they do better together./ Sometimes an animal has a plant partner./ The relationship develops until the two partners cannot manage without each other./ This is so in the corals of the sea./ In their skins they have tiny plants which act as "dustman"/ taking some of the waste products from the corals/ and giving in return oxygen which the animal needs to breathe./ If the plants are killed,/ or are even prevented from light so that they cannot live normally,/ the corals will die.
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