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  3. Man has invented ways to keep warm, but how do animals defend themselves? They cannot reason in the sense that man can, but natu

Man has invented ways to keep warm, but how do animals defend themselves? They cannot reason in the sense that man can, but natu

admin2013-12-08  50
问题     Man has invented ways to keep warm, but how do animals defend themselves? They cannot reason in the sense that man can, but nature has taken care of the animal kingdom by providing animals with special instincts. One of these instincts is known as hibernation(冬眠).
    "Sleeping like a dormouse(睡鼠)" is not only a common saying but a reality. When winter comes, the dormouse and other hibernating animals have reached a well-nourished state. They eat very well in warmer days laying down fat in the tissues of their bodies and during hibernation this keeps them alive. Safe in their nests, or burrows, they sleep soundly until the warmth of spring arrives. Bats, tortoises, snakes, frogs, even insects like butterflies, hibernate more or less completely. Some, like the squirrels, sleep during coldest weather but are roused by a warm spell. During hibernation, the temperature of an animal’s body drops drastically. Breathing and heartbeats almost cease.
    Another instinctive methods of avoiding intense cold is to escape by means of migration. Wild swans, seagulls, swallows and cuckoos are a few of the very many kinds of birds which fly thousands of miles, twice a year, to avoid cold. Many animals, especially those of the Arctic regions, have summer and winter quarters. The Arctic deer of North America, as well as the reindeer of Europe, move southward towards the forests when winter approaches. They return to the northern area when the warmth of spring begins to be sensed. There are animals which do not attempt to leave at the first sign of winter cold. Their instinctive means of defense is to dig out a deep burrow, made soft and warm by padding out with straw, leaves, moss and fur. In it they have a "secret place" containing food which they hope will last the winter through! Animals which fall into this class include the Arctic fox, the rabbit and the ermine(貂)and the little field-mice.
During hibernation, animals breathe______.
选项 A、normally
B、at a much slower rate
C、at a faster rate
D、irregularly
答案B
解析 本题为事实细节题，提问的是动物冬眠时的呼吸情况。根据第二段最后一句话“Breathing and heartbeats almost cease．”可知，冬眠中的动物的呼吸几乎停止，所以答案为B)。
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