语篇出处：2019年全国卷Ⅰ 语篇类型：说明文 主题语境：北极熊
The polar bear is found in the Arctic Circle and some big land masses as far south as Newfoundland. While they are rare north of 88°， there is evidence __1__ they range all the way across the Arctic, and as far south as James Bay in Canada. It is difficult to figure out a global population of polar bears as much of the range has been __2__ (poor)studied; however, biologists calculate that there are about 20,000－25,000 polar bears worldwide.
Modern methods __3__ tracking polar bear populations have been employed only since the mid1980s, and are expensive __4__ (perform) consistently over a large area. In recent years some Inuit people in Nunavut __5__ (report) increases in bear sightings around human settlements, leading to a __6__ (believe) that populations are increasing. Scientists have responded by __7__ (note) that hungry bears may be congregating (聚集) around human settlements, leading to the illusion (错觉) that populations are __8__ (high) than they actually are. Of __9__ nineteen recognized polar bear subpopulations, three are declining, six __10__ (be) stable, one is increasing, and nine lack enough data.
