【正确答案】
D
【答案解析】[听力原文]
In Spring 2008, the polar bear was placed on the endangered species list. {{U}}According to the Endangered Species Act, an endangered species is an animal that is likely to face extinction in its natural habitat.{{/U}} Polar bears have been categorised as a "threatened" species. The ESA defines a threatened species as one that is likely to become "endangered" in the foreseeable future. {{U}}The polar bear is the first animal that has been classified as endangered due primarily to global warming.{{/U}} Global warming is caused by carbon dioxide and other green-house gases that become trapped in the atmosphere. Heating homes, driving cars, and burning garbage all require fossil fuels that lead to global warming. {{U}}The polar{{/U}} {{U}}bear's habitat is more vulnerable to global warming than many other species.{{/U}} Polar bears live mainly on the sea ice in the Arctic. This is where they hunt for fish and build up fat reserves. When the ice melts many polar bears move to land and live off their stored fat. In the Arctic, global warming is causing the ice to melt slightly earlier and from slightly later. This results in a shorter feeding season for the polar bear. Some risk their lives to find ice. If they have to swim too far they will drown from exhaustion and hunger. {{U}}The World Wildlife Fund estimates that nearly 25% of the Arctic sea ice has disappeared in the past 20 years.{{/U}} Since the Endangered Species Act was introduced in the US in 1973, many species have been taken off the list due to increased populations.
What is an endangered species, according to the passage?
[解析] 短文开头提到an endangered species is...that is likely to face extinction in its natural habitat，由此可知，答案为D。
选项中one that is...extinct/...dangerous和natural表明，本题是关于某一类动物的定义。
D中的natural home与短文中提到的natural habitat对应。
【正确答案】
C
【答案解析】[听力原文]
What poses the greatest threat to polar bears today?
[解析] 短文中提到，the polar bear is the first animal...endangered due primarily to global warming以及the polar bear's habitat is more vulnerable to global warming，由此可知，气候变化对北极熊造成了很大的威胁，故答案为C。选项中的polluted water，climate change和over-hunting表明，本题可能考查某种生物减少或灭绝的原因。
due to意为“由于”，表原因。表原因处为常考点，听音时应注意。