As our boat moves quickly up and down in a windy ice-filled small bay，I try to judge the health condition of the polar bear （北極熊）in front of me.We are in Franz Josef Land，a remote part of Russia between the Barents Sea and the Arctic Ocean.
   While offshore bears follow the sea ice，hunting seals （海豹）on ice all year round，bears that live by the sea spend their summers on land and are forced to search for whatever they can find.Relying on low-calorie meals such as the eggs of nesting seabirds，it is harder for these bears to pack on the pounds.Researchers recently found that offshore bears around the Barents Sea are some of the most polluted animals on Earth.This is a direct consequence of the seals they feed on.
   Over a period of 14 years' study，Heli Routti from the Norwegian Polar Institute found that offshore female bears were in a better health，having greater body weight，than female bears by the sea，but on average their levels of pollutants called PFASs are 33 percent higher.
   PFASs are used to make industrial products which are poisonous and degrade （降解）very slowly.These pollutants find their way to the Arctic through air，where they fall in snow and gradually add up in the ice.As the ice melts every summer，the PFASs go into the water，where they enter the food chain.They eventually make their way into the fat that keeps seals warm and from there into the bears that eat them.
   During my 15 days in Franz Josef Land，I saw five bears，all living by the sea.Each looked relatively healthy.There are signs that these bears are dealing with the global-warming-caused ice loss relatively well. "The bears，so far，seem to be handling the sea ice loss，" says Andrew Derocher at the University of Alberta，who worked with Routti on the study，"But I'm sure that's going to change if the speed of ice loss increases sharply in the area."

（1）From the text we can learn polar bears living by the sea

B

B

.
A．eat seals on ice all year round
B．look for food on land in summer
C．become the most polluted animals on Earth
D．stay on the ice in summer to avoid hot weather
（2）What does the underlined part "pack on the pounds" in Paragraph 2 mean？

A

A

A．Put on weight.
B．Move around.
C．Fight against pollution.
D．Live alone.
（3）What is Paragraph 4 mainly about？

C

C

A．The rate of PFASs' degradation.
B．The effects of PFASs on the environment.
C．The process of PFASs' entering polar bears.
D．The application of PFASs in modern industry.
（4）According to Andrew Derocher，what will happen if the sea ice loss increases？

D

D

A．More pollutants may go into the air.
B．It will make no difference to bears.
C．The death rate of seals may increase.
D．Bears might fail to adapt to the change.