decline in the Hudson Bay polar bear population over the past ten years- a fall clearly caused by global warming.РBesides, a growing number of polar bears may be drowning (溺水) as they are forced to swim more often, and for longer distances, looking for ice sheets(冰原). According to a report by the US Mincrals Management Service, researchers observed four dead polar bears floating 60miles off Alaska in September of2006 and said it was likely that many other bears swimming far off shore also drowned. Scientists have concluded that the worldwide population of about 20,000polar bears is likely to e smaller by more than 30 percent in the next 35 to 50 years alone.Р12. What do polar bears usually do in summer?РA. Look for relatives.РB. Hunt for food.РC. Store crops up.РD. Make friends with seals.
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