专四专八考试

【单选题】 Questions 23～25 are based on the following news from theBB
C、or the VOA、At the end of the news item, you will be given 15 seconds to answer the three questions. Now listen to the news.
The search for a cheap alternative fuel has ledAmerican scientists to study the potential of ______.A．sunlight
B．pure hydrogen gas

C、pond water
D．small stream

网考网参考答案：C
网考网解析：
[听力原文]23-25 The search for a cheap alternative fuel to take the place of petroleum has led American scientists to study the potential of pond water. They are interested in a green scum known as algae that forms on the surface of stagnant pools. Helen Briggs reports from Washington: "Scientists have found a way of harnessing the natural ability of algae under certain conditions to make pure hydrogen gas from sunlight and water The researches based in California and Colorado describe the new discovery as the equivalent of striking oil. But there are still big obstacles to be overcome. The technique’s only been tried on a small scale in a laboratory and to be commercially viable, use of hydrogen and gas must be increased by a factor of ten. If they do manage to make the process work, perhaps in 20 years’ time, researchers say a small pond of algae could produce enough hydrogen gas to meet the weekly fuel needs for a dozen or so cars. [点拨] 抓住句子"The search for a cheap alternative...study the potential of pond water."。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>