Read the following passage and mark the letter A, B, C, or II to indicate the correct word or phrase that best fits each of the numbered blanks.
Some animals hibernate or go into a deep sleep as an adaptation to the cold months of winter. Hibernation is different from normal sleep. During hibernation, an animal seems to be dead. Its metabolism slows down and its body temperature (46) ______. Its heartbeat slows to only two or three beats a minute. Since its bodily processes are so slow, it needs very little food to stay (47) ______. Some animals which hibernate are toads, skunks, ground squirrels, bees, and bats. Bears sleep during the winter, but they are not (48) ______ hibernators. They wake up when they hear loud noises. Some animals estivate, or go into a deep sleep as an adaptation (49) ______ the hot, dry months of summer. During estivation, an animal's heartbeat and breathing slow down. During estivation, an animal does not glow or move, It does not need to eat because it is not using much energy. Some animals burrow underground, (50) ______ it is cooler, before they begin to estivate. Some aniriials which estivate are reptiles, bees, hedgehogs, frogs, toads, and earthworms.
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Điền vào số: 48
A. factual
B. rightly
C. authentic
D. true