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(单词翻译:双击或拖选)
Are aliens going to eat us? Signed, Frightened. Well, Frightened That’s more of a science fiction question. But science does have something to say you, and sometimes purely1 imaginative questions are great tools for helping2 us think about how the real world works. First, it’s not strictly3 impossible. Many scientists agree that the Milky4 Way galaxy5 is probably brimming with living things. That doesn’t mean any of them are smart enough to build interstellar spaceships, but let’s assume they are. Still, why are they unlikely to eat us? One reason lies in energy itself. The point of eating is to take in usable energy. A lion will expend6 a lot of energy running down a zebra because, once it is caught, the calories contained in the meal far outweigh7 those expended8 in the chase. If this weren’t true–say, if the zebra’s body only had the caloric content of a grape–then the energy expended would outweigh the energy gained, and the lion would lose out. Any alien predators9 would face the same problem. The amount of energy expended in building a space program, fueling rockets, to say nothing of getting from one star to another, would be huge. For any realistic technology it would far outweigh the benefit of just munching10 on people. It would be like climbing Mount Everest in order to pick a few berries. Some day we ourselves may travel to other planets. But any species that goes to such lengths merely to find food will find itself quickly exhausted11.
1 purely | |
adv.纯粹地,完全地 | |
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2 helping | |
n.食物的一份&adj.帮助人的,辅助的 | |
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3 strictly | |
adv.严厉地,严格地;严密地 | |
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4 milky | |
adj.牛奶的,多奶的;乳白色的 | |
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5 galaxy | |
n.星系;银河系;一群(杰出或著名的人物) | |
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6 expend | |
vt.花费,消费,消耗 | |
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7 outweigh | |
vt.比...更重,...更重要 | |
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8 expended | |
v.花费( expend的过去式和过去分词 );使用(钱等)做某事;用光;耗尽 | |
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9 predators | |
n.食肉动物( predator的名词复数 );奴役他人者(尤指在财务或性关系方面) | |
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10 munching | |
v.用力咀嚼(某物),大嚼( munch的现在分词 ) | |
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11 exhausted | |
adj.极其疲惫的,精疲力尽的 | |
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