阅读理解 Passage 2 The top of the world is a wonderland. In winter, the temperature often falls to -30°F and the sun never rises. The ocean is surrounded by frozen ground. There are few people or trees, but to polar bears, the Arctic(北极)is home. (78) Polar bears have thick fur, big paws and other features that make them well prepared for life in their tough environment. In fact, they need the Arctic sea ice for survival. But climate change is causing larger and larger areas of summer sea ice to melt(融化). Experts say that if warming patterns continue, the Arctic could be free of summer sea ice by 2050. That may cause two-thirds of the world’s 20,000 polar bears to be gone by then too. Polar bears can’t survive for long on land. Seals are their main source of food. The only place where polar bears can hunt seals is on the ice. (79) Although these bears are strong swimmers, they are no match for lightning swift seals in the water. A polar bear has brilliantly clever strategies to overcome this disadvantage. In winter the bear waits motionless beside a seal’s breathing hole, which is a narrow tunnel through the ice. Often many hours pass before the seal comes up for air and the bear kills it with a powerful blow of its paw. In summer, the polar bears that live on land eat very little and wait for the sea ice to return. With the sea ice forming later in the year and melting earlier, polar bears do not have enough opportunity to hunt and eat. Less sea ice makes it harder for the bears to catch the seals. The bears must swim longer distances between ice packs(大片浮冰), and they can’t always make it. The ice is also getting thinner. These conditions can cause polar-bear cabs to become separated from their mothers, who provide them with food. Steven Amstrup is the chief scientist of Polar Bears International. The group aims to save the bears and their home. "The more people who see polar bears and understand their difficult situation, the better the chance we’ll alter our warming path in time to save them," he says.

单选题 Which is the best title for the passage?

【正确答案】 D

【答案解析】[解析] 全文的每段首句为最先定位点。每段的末句也可以成为辅助。主旨题。从第一段中提到polar bear开始，之后的每段首句都说到了polar bear，因此，这个词就成为了全文的中心话题。再根据第二段的末句以及第三段的首句，第四段首句，第五段的首句，可以看出，全文讨论的重心是在环境变化给北极熊带来的生存危机。故选D。

单选题 Where do polar bears usually hunt seals?

单选题 The word "cubs" in the fourth paragraph is closest in meaning to_____

【正确答案】 B

【答案解析】[解析] 根据线索词cubs，定位至第四段最后一句“These conditions can cause polar-bear cubs to become separated from their mothers, who provide them with food.”。词汇题。阅读理解中的词汇题考的永远不是词汇本身，而是联系上下文对文章的理解。因此找到包含考查词汇的句子后，要先通读整个句子。我们在这个句子中发现cubs之后出现their mothers，可以推断，cubs和mothers是相对应的，因此意思是“孩子”。故选B。

单选题 According to the passage, which of the following statements is TRUE?

A、 Starving polar bears are increasingly coming into villages, where they may be killed either for food or safety.
B、 Polar bears can spend their entire lives on land if the sea ice melts completely.
C、 Two-thirds of the world’s polar bears may disappear by 2050 as global warming continues.
D、 The growing distance between ice packs is not a problem for polar bears, because they are excellent swimmers.

【正确答案】 C

【答案解析】[解析] 此类题型的定位比较繁琐，因为在题干中无法寻找到定位线索词，做题的方法为——从选项入手，找到各个选项的关键词，雨分别到原文定位。细节题。A选项中提到北极熊因为饥饿而闯入村庄——coming into village，这个在原文中没有信息提到，所以排除。B选项中的spend their lives on land帮助我们定位到原文的第三段开头——polar bears can't survive for long on land.与选项意思正好相反，所以排除。原文第二段最后一句That may cause two-thirds of the word's 20, 000 polar bears to be gone by then too.及前一句…the Arctic could be free of summer sea ice by 2050与C选项信息一致。原文第四段第三何话The bears must swim longer distances between ice packs(大片浮冰)，and they can't always make it.与D选项中not a problem意思相左，因此排除。故选C。