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Scientists have long wondered what benefit zebras might get from their fancy black-and-white coats. Those stripes (条纹) may be most useful as protection from biting flies, a recent study concludes.

Biologists studied zebras and other closely related African animals. They tested five popular ideas about how the stripes might function. No evidence emerged to support most of these notions, Tim Caro told Science News. A wildlife biologist, he works at the University of California, Davis.

  ①   .Some scientists had proposed those stripes help zebras hide from predators (食肉动物), such as lions, or confuse them. Still others suggested that those stripes might offer some cooling or help the animals in forming social groups.

     ②    . Instead, the stripes appear to help the animals avoid the bite of bloodthirsty flies. This finding supports some studies had found signs that flies prefer solids to stripes when hunting for a landing place.

     ③   .To test all of the theories, Caro's group used geographic information. They looked at where in Africa the 20 different types of animals belonging to the genus Equus lived. Some of these equines (马科动物) have stripes, including zebras and asses (驴) with striped legs. Others are stripe-free. These include other asses and wild horses.

The scientists found no connection between stripes and whether the animals lived in woodsy(树林多的)areas. That suggests stripes don’t camouflage(伪装)zebras in those places.

    The scientists also saw no link between where striped animals lived and where lions hunted. In ether studies, researchers found that lions ate plenty of zebras. The new observations suggest stripes don't confuse the predators.

    The experts also looked for-and found-no evidence that stripes cool the zebras or help them recognize each another when forming social groups.

     ④   .Striped animals often live in places where the environment is just right much of the year for biting flies to flourish. In those areas, horseflies, tsetse flies(舌蝇)and other biting flies spread fatal diseases to zebras and horses. That connection now suggests stripes may help zebras reduce the number of bites-and the infections they can spread.

    The study doesn't answer how the zebra got its stripes in the first place, Caro admits. Science may never know. Inns Cuthill is a biologist at England's University of Bristol. He finds the new study “compelling(令人信服的)”，Until now, Cuthill's favorite hypothesis had been that zebra stripes confused predators. It's too soon to say the mystery of the zebra's stripes has been solved, he notes. But he says that keeping flies away is now probably “the leading contender.”

63. According to the recent study, the stripes in zebras may be used to      

    A. offer some cooling when it is hot

    B. help them hide from or confuse predators

    C. protect themselves from being bitter, by flies

    D. help them in forming social groups

64. The missing sentence “None of those ideas make sense.” can be put in      

    A.①      B.②      C.③     D.④

65. It can be inferred from the passage that         

    A. The study answers how the zebra got its stripes

    B. Flies prefer solids to stripes when seeking a landing place

    C. Cuthill now tends to believe the new theory

    D. The mystery of the zebra's stripes will be solved soon

66. Which of the following can best serve as the title of this passage?

    A. One Plus to Wearing Stripes             B. How Does Zebra Get Stripes

    C. Mystery Solved                       D. Zebra's Stripes
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