In the following text, some sentences have been removed. For Questions 1~5, choose the most suitable one from the list A~G to fi

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问题     In the following text, some sentences have been removed. For Questions 1~5, choose the most suitable one from the list A~G to fit into each of the numbered blanks. There are two extra choices, which do not fit in any of the blanks.
    For the endangered North Atlantic right whale, these arc trying times. These leviathans who live and migrate in waters along the East Coast of North America teeter closer to the brink of extinction than perhaps any other whale species. Their population is tiny—less than 350—and continues to shrink.【C1】______
    Yet for scientists and conservationists anxious about the future of these creatures, rays of hope are beginning to pierce an otherwise gloomy horizon. Thanks to a surge of scientific research and new tools for conducting it, they expect to learn far more about right whales, their interaction with the environment, and how to better protect them from their biggest threat: man.【C2】______
    For the right whales, the leading causes of mortality are collisions with ships and encounters with fishing gear, researchers say. Females appear to have the toughest time surviving the range of human and natural threats. It’s these challenges scientists hope to address with a growing momentum in right-whale research.
    【C3】______ Conservationists are working with governments and the shipping industry to move or control traffic on heavily used sea lanes that ships and whales share. And recent research is yielding potentially useful insights into the impact of factors ranging from water quality to shifts in climate.
    "I’m not much of a Pollyannaj 1 can be very grumpy about the progress of right-whale biology and conservation," says Scott Kraus, director of research at the New England Aquarium in Boston. But "in the next couple of years we’re going to see a tremendous burst of very creative scientific energy" applied to fundamental biological and ecological questions surrounding the whales.
    "When those questions get answered, we’ re going to have very specific ideas about what management strategies will reduce mortality and perhaps enhance reproduction," he says.
    【C4】______ In principle, preventing "two female deaths a year would have a major impact on the prospects for the population," says Hal Caswell, a marine zoologist at the Woods Hole Oceanographic Institution in Woods Hole, Mass.
    【C5】______
    From 1500 to 1600, Basque whalers decimated right-whale populations in the eastern Atlantic, taking an estimated 25,000 to 40,000. In the late 1600s, by some accounts, it would have been possible to walk across Cape Cod Bay on the backs of whales. But by the mid-1700s, New Englanders had taken another 3,000, Mr. Kraus says. By the early 20th century, "only a few dozen whales survived in the western North Atlantic".
    [A]If they can save a population this small, then it could boost hopes of saving other species from the unintended impact of humans on the environment.
    [B]Yet achieving that means untangling a web of intertwined human and environmental factors that contribute to the whales’ plight. The one factor that weighs most heavily is human.
    [C]In addition, researchers are exploring a number of acoustic approaches to avoiding ship-whale collisions. One technique scientists hope to test later this month involves the use of moored buoys that use passive sonar systems to listen for whales.
    [D]To an outsider, the goal looks deceivingly within reach. The population is so small that it would take only modest pains in saving whales to help turn the situation around.
    [E]That population had slowly rebuilt. Over the past 20 years, researchers have built an impressive collection of 250,000 photos—a catalog of some 460 North Atlantic right whales. Each animal bears unique growths of hardened skin, or callosities, in places where hair would appear on humans. The callosity patterns act as visual tags, allowing researchers to follow the whales’ life history.
    [F]Later this month, for example, researchers are set to test new approaches to tracking the elusive whales in hopes of alerting ships to their presence. Meanwhile, chemists and engineers are developing whale-friendly commercial-fishing gear.
    [G]By some estimates, if current population trends hold, the species will vanish within the next 200 years.
【C5】

选项

答案B

解析 本题独立成段,可联系上下文获得答题线索。上文指出研究表明防止雌性鲸鱼的死亡对保持鲸鱼数量有明显作用。下文则论述了16世纪到20世纪鲸鱼数量在人类活动影响下的变化。可知本题内容应与人类活动对鲸鱼数量的影响有关。因此选项B为最佳选项。
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