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）

that

that

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）

poorly

poorly

（poor） studied；however，biologists calculate that there are about 20，000-25，000 polar bears worldwide.
   Modern methods （3）

of/for

of/for

tracking polar bear populations have been employed only since the mid-1980s，and are expensive（4）

to perform

to perform

（perform） consistently over a large area.In recent years some Inuit people in Nunavut（5）

have reported

have reported

（report） increases in bear sightings around human settlements，leading to a（6）

belief

belief

（believe） that populations are increasing.Scientists have responded by（7）

noting

noting

（note） that hungry bears may be congregating （聚集）around human settlements，leading to the illusion （錯覺） that populations are（8）

higher

higher

（high） than they actually are.Of （9）

the

the

nineteen recognized polar bear subpopulations，three are declining，six （10）

are

are

（be） stable，one is increasing，and nine lack enough data.