题目内容
阅读理解
阅读下列短文,从每题所给的A、B、C、D四个选项中选出最佳选项。
To many web building spiders, most of whom are nearly blind, the web is their basic window on the world: their means of communicating, capturing prey, meeting mates and protecting themselves. A web - building spider without its web is like a man isolated on an island of solid rock, totally out of touch and for sure to starve to death.
So important is the web to a web spider's survival that the animal will continue to construct new webs daily even if it is being straved. For 16 days the starving spider builds completely normal webs. Then, as the animal gets much thinner, it constructs a web using fewer strands. Such webs would only trap larger prey, which is more economical from the view of a starving spider.
The spider preserves energy by recycling web protein (蛋白质). It simply eats its own web each evening and re - uses it to manufacture new silk. In studies with redioactively labeled materials, it was found that 95 percent of web proten reappears in the next day's web. Most of the energy needed for web - building is used in walking over the strands (线,绳) as they are laid down.
Scientists are impressed by the adaptability of the spider's highly preprogrammed brain, which is larger for its size than the brain of any other invertebrate (无脊椎动物). If web - building is interrupted, or if some of the existing strands are destroyed, the spider simply retraces its steps to see where the web is left off and then finishes building a normal web. One spider will even finish building the incomplete web of another.
1.That a spider is able to finish an incomplete web of another proves that ________.
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A.a spider re - uses its web energy to reproduce new silk
B.spiders have a highly preprogarmmed brain
C.the web is everything to a spider
D.a spider is able to mend a destroyed web
2.A spider preserves its energy ________.
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A.because it constructs new webs daily
B.as it walks over the strands it lays
C.by eating its own web protein and then re - using it in the new web
D.by eating only in the evening
3.Without its web a web - building spider would NOT be able to ________.
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4.The underlined word “isolated” in the first paragraph means ________.
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