When ice is on the ocean， the polar bears are on the hunt． They are hunting seals．Polar bears need the ice． They can't catch seals as well in the water， where there is no ice．

    In summer， some of the sea ice becomes water．Now，however， the sea ice is becoming water earlier than it used to．There is not as much time for the polar bears to hunt for food．They should have enough fat in their bodies to keep them from getting hungry．Some polar bears， however，haven't been able to get enough to eat． By the end of the summer， they are going to die．

    Scientists want to learn all they can about polar bears and how they can help them．To help the bears，they have to do tests．It is difficult， however，for scientists to get close to the bears．Scientists fly in a helicopter， over the places where polar bears live．When they notice a bear， they shoot a pointed object at it． The object makes the bear go to sleep．While the bear is asleep，the scientists can do their tests．The most important test is the fat test． If the bear hasn't eaten for two months， it won't have enough fat to live on．

    Many people are worried about the ice that is becoming water．Polar bears have to go further and work harder to find food． If the ice keeps becoming water， one day there might not be any polar bears．

（1）The underlined word "hunt" in the first paragraph means：　　．

A．搜集

B．游荡

C．狩猎

D．探索

（2）If polar bears want to find food，what do they need？　　

A． Fat．

B． Ice．

C． A pointed object．

D． Water．

（3）What's the main idea of this passage？　　

A． Polar bears are in great danger．

B． Polar bears like hunting for seals to eat．

C． It's difficult for scientists to test bears．

D． The ways to help polar bears．