but difficult many complete which spend they on do appear die it.

Scientists predict that most polar bears（北極熊）（1）

will disappear

will disappear

by the year 2100 because of global warming（全球變暖）.Even if global warming is slowed down ，the number of the polar bears will still be seriously influenced.
   Scientists think there are about 25，000 polar bears left.Polar Bears（2）

spend

spend

most of their lives on the ice（3）

which

which

covers the Arctic（北極的） sejye.ai.As the world gets hotter，the Arctic is warming about twice as quickly as other places.This is making the ice cap smaller and thinner.Scientists say that the ice could melt（融化）（4）

completely

completely

during the summers by 2040.For polar bears，that's a matter（大事） of life and （5）

death

death

.Polar bears depend（6）

on

on

the sea ice to travel，find mates（配偶），and hunt（打獵）.
   In the winter，when there's enough ice，polar bears eat as （7）

much

much

as possible to store up energy.But if there's less winter ice，polar bears will have less area for hunting.
   Summers are the（8）

most difficult

most difficult

time for polar bears.With less ice to travel on，they have to spend more time on land，where there isn't much food.Polar bears have no choice （9）

but

but

to go as long as six months without food.But rising temperatures in the Arctic are causing the days without ice to come sooner and last longer.That means the bears have no food to eat for a very long time.The lack of food may make baby polar bears live much harder.If they can't live through the summers，it is possible for polar bear numbers to drop quickly.
   Scientists warn that if global warming continues，only the polar bears in the coldest parts of the Arctic will survive（幸存）.
   Something must（10）

be done

be done

to help save polar bears.Mans need to take actions to slow the global warming down.As researcher Peter Molnar says，"It is hopeful that they are not completely disappeared，if we change our behaviors."