【正确答案】 A

【答案解析】[听力原文]33-35 Millions of years ago, whales lived on land and walked on four legs. Today，whales still have small bones that are the remains of their hind legs, but these bones can only be seen on the inside of the whale. No one knows why whales left the land to live in the water. However, scientists can imagine that when the whales changed their environment, their bodies underwent a change—taking on a more fish-like appearance. This new form offered less resistance to the water, enabling the whales to swim faster. Despite their fish-like form, whales are not fish. A whale will drown, just as a man will, if it stays under water too long. When a whale is under water, it closes its nostrils tightly and holds its breath. The air in its lungs becomes very hot and full of water vapor. When the whale rises to the surface and exhales, its hot breath produces a column of water vapor that rises high in the air. A man produces the same effect when he exhales warm air on a cold morning. Whales are classified as mammals because they bear their young, rather than laying eggs, and because the mother whales give the babies milk. Like other mammals, whales have warm blood. Their blood stays at the same temperature, even when they move from hot to cold water. They keep warm in cold water because they have a thick layer of fat just under their skins. This fat is called blubber, and it is thicker on whales that spend their lives in cold water. Almost all land mammals, except man, have hair on their bodies to keep them warm, but whales, which have very few hairs, are kept warm by their fat. 33．How does a whale keep itself warm? [答案解析] 细节题。根据文中提到的They keep warm in cold water because they have a thick layer of fat just under their skins.(因为它们皮下有一层厚厚的脂肪，所以在冷水中可以用来保暖。)可知，鲸靠皮下脂肪取暖，答案是A。 [圈定关键词] fat, moving, blood temperature, hot air [听前预测] 根据选项中出现的关键词可以推断文章同某种动物有关，因为单词whale的出现，猜测该种动物可能是鲸鱼。同方式有关。

【正确答案】 B

【答案解析】[听力原文] What do we learn about the blood temperature of a whale? [答案解析] 细节题。文中提到的Their blood stays at the same temperature, even when they move from hot to cold water.(即使是从暖水游到冷水，它们的体温也保持不变。)表明，鲸的体温是恒定不变的，答案是B。 [圈定关键词] blubber, the same, water temperature, grows older [听前预测] 根据选项中出现的关键词可以推断文章同某种动物有关，因为单词whale的出现，猜测该种动物可能是鲸鱼。同温度有关。

【正确答案】 A

【答案解析】[听力原文] In what way do whales distinguish themselves from other land mammals? [答案解析] 细节题。根据原文中的最后一句话Almost all land mammals, except man, have hair on their bodies to keep them warm, but whales, which have very few hairs, are kept warm by their fat.(除了人以外，几乎所有的陆地哺乳动物都靠身上的毛取暖。而鲸鱼身上几乎没有毛，是靠它们的脂肪取暖。)可知，鲸和其他哺乳动物的区别在于取暖方式不同。选项A同原文的意思一致。B、C、D选项在文章中均有提及，都是鲸鱼与其他哺乳动物的相似之处。答案是A。 [圈定关键词] hairs, bear their young, lungs, hind legs [听前预测] 根据选项中出现的关键词可以推断文章同某种动物有关，因为单词whale的出现，猜测该种动物可能是鲸鱼。同该种动物的特点有关。