[請益] Powering the industrial revolution

看板TOEFL_iBT (TOEFL_iBT托福)作者ipathigo (機哩呱啦)時間15年前 (2010/12/05 16:31)推噓1(1推 0噓 0→)

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Paragraph 2: The source had long been known but not exploited. Early in the century, a pump had come into use in which expanding steam raised a piston in a cylinder, and atmospheric pressure brought it down again when the steam condensed inside the cylinder to form a vacuum．This “atmospheric engine,” invented by Thomas Savery and vastly improved by his partner．Thomas Newcomen, embodied revolutionary principles, but it was so slow and wasteful of fuel that it could not be employed outside the coal mines for which it had been designed. In the 1760s, James Watt perfected a separate condenser for the steam, so that the cylinder did not have to be cooled at every stroke; then he devised a way to make the piston turn a wheel and thus convert reciprocating (back and forth) motion into rotary motion. He thereby transformed an inefficient pump of limited use into a steam engine of a thousand uses. The final step came when steam was introduced into the cylinder to drive the piston backward as well as forward thereby increasing the speed of the engine and cutting its fuel consumption. 5. According to paragraph 2，the atmospheric engine was slow because ○it had been designed to be used in coal mines ○the cylinder had to cool between each stroke ○it made use of expanding steam to raise the piston in its cylinder ○it could be operated only when a large supply of fuel was available Ans:(B) 想請問C為什麼不對如果我只看 the atmospheric engine的前一句“a pump had come into use in which expanding steam raised a piston in a cylinder”看起來C也沒有問題，而且這題的答案是在蠻後面"so that the cylinder did not have to be cooled at every stroke"，這個答案也沒有很明確的說明是造成slow的原因好苦惱阿~~~~ 麻煩各位解答一下了謝謝!! -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 140.135.166.89