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  3. Renewable energy, it turns out, does grow on trees. The fruit pods plucked from jatropha trees have seeds that produce clean-bur

Renewable energy, it turns out, does grow on trees. The fruit pods plucked from jatropha trees have seeds that produce clean-bur

admin2012-06-02  44
问题     Renewable energy, it turns out, does grow on trees. The fruit pods plucked from jatropha trees have seeds that produce clean-burning diesel fuel. But unlike corn and other biofuel sources, the jatropha doesn’t have to compete with food crops for arable land. Even in the worst of soils, it grows like weeds. Sound too good to be true? That’s why brothers Paul and Mark Dalton chose to name their Florida jatropha company My Dream Fuel.
    If President Barack Obama’s green-energy rhetoric is on the level, this should be the year the U. S. gets clued in to what much of the rest of the world is already betting: that jatropha, like other nonfood sources such as algae, will revive a biofuels movement battered of late by charges that it diverts too many crops from too many mouths. India has set aside 100 million acres for jatropha and expects the oil to account for 20% of its diesel consumption by 2011. Australia, China, Brazil and Kenya have also embraced it. In December, a Boeing 747 was successfully test-flown by Air New Zealand using a 50-50 blend of jatropha and aviation fuel.
    "This is a superior biodiesel, " says Roy Beckford, a University of Florida researcher and expert on sustainable farm development. He has been studying different varieties of jatropha and in February plans to publish his findings that trees like those the Daltons are growing (since 2006 they’ve planted 900,000 near Fort Myers) thrive so well in Florida that they may yield up to eight times as much oil as they do in places like India and Africa.
    Native to the Caribbean, jatropha curcas was taken to India in the 1600s by Portuguese sailors who used the seeds for long-burning lamp oil. When Paul Dalton, 54, a Washington attorney, decided to invest $ 500,000 in an alternative-fuel venture, he followed the Portuguese trail to India and found prolific new jatropha varieties being cloned in the city of Mysore. The fuel emits negligible greenhouse gases, and the trees can capture four tons of carbon dioxide per acre (which might make growers eligible for carbon credits on the global market). Says Ron Pernick, co-founder of the alternative-energy research firm Clean Edge, "Jatropha isn’t a silver bullet, but it looks very promising. "
    That’s good news not only for energy gluttons like the U. S. but also for energy-starved nations like Haiti, which rarely has enough diesel to power its capital for a full day. My Dream Fuel donates jatropha trees to Caribbean countries in the hope that they won’t have to choose between producing enough fuel and producing enough food. "We want to make money with jatropha, but we also want to make a difference, " Paul Dalton says. If jatropha can do both, it’s an idea that could grow like weeds.
Para. 4 mainly tells us
选项 A、jatropha’s bright future with its advantages.
B、jatropha’s long history as a biofuel.
C、jatropha’s advantages as a biofuel.
D、many cloned prolific varieties of jatropha in India.
答案A
解析 段落主旨题。该段主要说明了麻风树的历史、优点以及广阔前景，其中它的优点和广阔前景无疑是本段的重点。由此可知，选项[A]“麻风树因其优势而具有广阔的前景”比较准确地表达了该段的大意，所以为答案。[B]“作为一种生物燃料。麻风树有悠久的历史”，这只是其中的部分内容，不能概括全段的大意；[C]“麻风树作为生物燃料的优点”，这也只是该段的部分内容，不能表达全段的大意，所以[C]也不正确；[D]“印度有许多麻风树的高产克隆品种”，这仅是该段提到的一种事实，更不能代表文章的大意，因此[D]也不正确。
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