A buoyant device, such as a cork or polystyrene ring, for keeping a person afloat in water.
救生圈，救生衣：一种有浮力的装置，如软木或聚苯乙烯圈，用来使人能浮在水中。
Picture an empty wine bottle with a cork secured at the top in the usual way. Inside the bottle a metal ring hangs suspended by a string.
设想一个空酒瓶，瓶口被软木塞以正常的方式塞住，瓶子里一个金属环悬挂在一根细绳上。
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