【正确答案】
C
【答案解析】[听力原文] What I'd like to discuss with you today is the polar bear. As I already mentioned on Tuesday, polar bears only live in the Arctic, primarily in northern Canada, northern Russia, and Alaska. If, for example, you are in southern Canada, you won't see any of these bears. Now, you're probably aware that the Arctic is an extremely harsh environment and one of the coldest places on Earth. But let me remind you of what it's really like in the Arctic, especially in late December or early January. The temperature frequently drops below minus 40 degrees centigrade and sometimes gets even colder! Combine that with strong winds, little or no sunlight, and very little vegetation, and what you get is an environment in which very few species are capable of surviving. The polar bear, however, thrives in this kind of environment. The polar bear spends his time roaming throughout the Arctic, walking on land and ice, swimming in freezing sea water and floating on sheets of ice while looking for seals, fish, and other food. Their favorite food is seals, which they find along the edges of the ice, in holes in the ice, and under cracks in the ice. Polar bears are much bigger than the brown and black bears. In fact, they're huge! They weigh up to 720 kg. And they're designed to survive in their environment. They have very thick, white fur, which helps them hide in the snow and ice and overcome the extreme cold. Polar bears are also strong swimmers. They have large front paws that amazingly allow them to swim a few hundred kilometers from land. Despite their impressiveness, polar bears, unlike black bears, are an endangered species. This is a result of global warming, which will be topic of our next film. The Arctic is becoming too warm for the bears. That ice I just mentioned to you is now disappearing! It breaks up much earlier in the spring, and now it's a lot further from land! Ice thickness in the Arctic has decreased by 40 percent in the last 30 years, and some scientists predict that the Arctic basin might not have any ice in another 50 years. For polar bears, this is terrible! Ice is essential to their existence! Less ice means fewer seals and less food. Polar bears do their hunting in the winter, but because the winter is getting shorter and because the ice is disappearing earlier, they have less time to restore their fat. In the summer, they're forced to remain on land for longer periods of time, and during that time, they live off the fat stored in their bodies. Thirty years ago, they spent just over three months on land. Now it's almost four months! This reduces their strength and energy. With less ice, polar bears must swim further to reach it. This further reduces their strength and energy. These circumstances have steadily decreased the bear population over the last 30 years. Where can we see polar bears according to the lecture? 讲座开头就提到polar bears only live in the Arctic，primarily in northern Canada，northern Russia，and Alaska，指出北极熊只是生活在北极地区，主要是加拿大北部，俄罗斯北部和阿拉斯加。选项中只有C项符合听力原文，故选C。
【正确答案】
B
【答案解析】[听力原文] What can we learn about polar bears? 关于北极熊，听力原文中提到They have very thick white fur, which helps them hide in the snow and ice and overcome the extreme cold，指出北极熊身上长着厚厚的白毛，可以帮助它们在冰天雪地进行隐藏，还有助于它们克服极度的寒冷，因而B项表述正确，故选B。原文中提到的北极熊的体重是720千克，不是72千克，因此排除A项；原文中指出北极熊可以游几百千米，而不是几百米，故C项表述错误；原文中明确提到Their favorite food is seals，指出北极熊最喜欢的食物是海豹，因此D项也可排除。
【正确答案】
A
【答案解析】[听力原文] What made polar bears become endangered? 听力原文中提到北极熊现在濒临灭绝，随后提到This is a result ofglobal warming, which will be topic of our next film. The Arctic is becoming too warm for the bears. 指出北极熊濒临灭绝是由于全球气候变暖，对于北极熊来说温度太高，并且后面又提到温度提升导致冰融化，进而导致北极熊的食物来源变少，导致其濒临灭绝，因而A项正确，故选A。