题目

  In simple words, hibernation is a state of deep sleep. Hibernation differs from normal sleep in various ways. Hibernating animals take a long time to wake up from their sleep. Turning or kicking their bodies does not seem to wake them up. Even after waking up from hibernation, these animals take some time to restart their normal activities. During hibernation, the heart rate slows down and some of the non-vital organs become entirely inactive. This is a state in which the body uses very little energy.    Winter is the time when food is less and weather rough. Animals have to spend a lot of energy finding food. Even if they succeed in finding anything, it is often not enough to make up for the loss of energy. Besides, the cold weather may often become a cause of death. As a result of all these, animals have to reduce their food demand by reducing energy requirements. This is achieved by hibernating throughout the winter.    Before the onset of winter, when there is plenty of food, animals eat overmuch and store much of the food in the form of fat. As winter arrives, they return to their home where they spend the rest of winter hibernating. As animals hibernate, their body temperature starts dropping due to lack of activity and metabolism（新陈代谢）. At one point, it is only a few degrees higher than the surrounding temperature. Whatever energy the body needs to perform certain tasks is got from the fat storage. Due to lack of activity, the fat burning process is slow and steady. The energy from fat is enough to keep the animal alive for the rest of the winter.    Hibernation differs for every species. For example, some animals like black bears may sleep for the whole winter without waking up while animals like, squirrels may wake up every 4 days to eat some food, pass waste matter from the body, and then go back to sleep. Hibernation in domestic animals may differ from that in the wild ones. As there is no food shortage for domestic animals, domestic animals hibernate as a result of their natural instinct but with more active periods in between.                                  Hibernation 71.         A state of deep sleep 72.          from normal sleep * Taking a time to wake up *Taking some time to 73.      their normal activities again * Using very little energy Reasons for hibernating * Not finding enough food to make up for the 74.        of energy *75.        in death due to the cold weather Features of hibernation *Body temperature dropping because of 76.      Activity and metabolism * Getting energy from the fat 77.         * Burning fat slowly and 78.          Hibernating habits of different species * Black bears: sleeping all 79.       the winter without waking up *Squirrels: waking up every 4 days for basic daily needs * 80.         animals: having more active periods 答案：71. Definition    72. Differences     73. start     74. loss      75. Resulting 76. lacking       77.storage        78. Steadily  79. through   80. Domestic  

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