gre阅读练习每日一篇(二十九)
<p> 掌握了<span word="gre">gre</span>阅读里的长难句，到了实战演习的时候了。<span word="gre">gre</span>阅读练习每日一篇帮助<span word="gre">gre</span>考生循序渐进地进行练习和总结。希望<span word="gre">gre</span>考生在进行<span word="gre">gre</span>阅读练习时，也按着考试时候的时间规定自己的练习，这样才能有效果。</p><p> <span word="The">The</span> <span word="use">use</span> <span word="of">of</span> <span word="heat">heat</span> <span word="pumps">pumps</span> <span word="has">has</span> <span word="been">been</span> <span word="held">held</span> <span word="back">back</span> <span word="largely">largely</span> <span word="by">by</span> <span word="skepticism">skepticism</span> <span word="about">about</span> <span word="advertisers">advertisers</span> <span word="claims">claims</span> <span word="that">that</span> <span word="heat">heat</span> <span word="pumps">pumps</span> <span word="can">can</span> <span word="provide">provide</span> <span word="as">as</span> <span word="many">many</span> <span word="as">as</span> <span word="two">two</span> <span word="units">units</span> <span word="of">of</span> <span word="thermal">thermal</span> <span word="energy">energy</span> <span word="for">for</span> <span word="each">each</span> <span word="unit">unit</span> <span word="of">of</span> <span word="electrical">electrical</span> <span word="energy">energy</span> <span word="used">used</span>, <span word="thus">thus</span> <span word="apparently">apparently</span> <span word="contradicting">contradicting</span> <span word="the">the</span> <span word="principle">principle</span> <span word="of">of</span> <span word="energy">energy</span> <span word="conservation">conservation</span> . <span word="Heat">Heat</span> <span word="pumps">pumps</span> <span word="circulate">circulate</span> <span word="a">a</span> <span word="fluid">fluid</span> <span word="refrigerant">refrigerant</span> <span word="that">that</span> <span word="cycles">cycles</span> <span word="alternatively">alternatively</span> <span word="from">from</span> <span word="its">its</span> <span word="liquid">liquid</span> <span word="phase">phase</span> <span word="to">to</span> <span word="its">its</span> <span word="vapor">vapor</span> <span word="phase">phase</span> <span word="in">in</span> <span word="a">a</span> <span word="closed">closed</span> <span word="loop">loop</span> . <span word="The">The</span> <span word="refrigerant">refrigerant</span>, <span word="starting">starting</span> <span word="as">as</span> <span word="a">a</span> <span word="low">low</span>-<span word="temperature">temperature</span>, <span word="low">low</span>-<span word="pressure">pressure</span> <span word="vapor">vapor</span>, <span word="enters">enters</span> <span word="a">a</span> <span word="compressor">compressor</span> <span word="driven">driven</span> <span word="by">by</span> <span word="an">an</span> <span word="electric">electric</span> <span word="motor">motor</span>. <span word="The">The</span> <span word="refrigerant">refrigerant</span> <span word="leaves">leaves</span> <span word="the">the</span> <span word="compressor">compressor</span> <span word="as">as</span> <span word="a">a</span> <span word="hot">hot</span>, <span word="dense">dense</span> <span word="vapor">vapor</span> <span word="and">and</span> <span word="flows">flows</span> <span word="through">through</span> <span word="a">a</span> <span word="heat">heat</span> <span word="exchanger">exchanger</span> <span word="called">called</span> <span word="the">the</span> <span word="condenser">condenser</span>, <span word="which">which</span> <span word="transfers">transfers</span> <span word="heat">heat</span> <span word="from">from</span> <span word="the">the</span> <span word="refrigerant">refrigerant</span> <span word="to">to</span> <span word="a">a</span> <span word="body">body</span> <span word="of">of</span> <span word="air">air</span>. <span word="Now">Now</span> <span word="the">the</span> <span word="refrigerant">refrigerant</span>, <span word="as">as</span> <span word="a">a</span> <span word="high">high</span>-<span word="pressure">pressure</span>, <span word="cooled">cooled</span> <span word="liquid">liquid</span>, <span word="confronts">confronts</span> <span word="a">a</span> <span word="flow">flow</span> <span word="restriction">restriction</span> <span word="which">which</span> <span word="causes">causes</span> <span word="the">the</span> <span word="pressure">pressure</span> <span word="to">to</span> <span word="drop">drop</span>. <span word="As">As</span> <span word="the">the</span> <span word="pressure">pressure</span> <span word="falls">falls</span>, <span word="the">the</span> <span word="refrigerant">refrigerant</span> <span word="expands">expands</span> <span word="and">and</span> <span word="partially">partially</span> <span word="vaporizes">vaporizes</span>, <span word="becoming">becoming</span> <span word="chilled">chilled</span>. <span word="It">It</span> <span word="then">then</span> <span word="passes">passes</span> <span word="through">through</span> <span word="a">a</span> <span word="second">second</span> <span word="heat">heat</span> <span word="exchanger">exchanger</span>, <span word="the">the</span> <span word="evaporator">evaporator</span>, <span word="which">which</span> <span word="transfers">transfers</span> <span word="heat">heat</span> <span word="from">from</span> <span word="the">the</span> <span word="air">air</span> <span word="to">to</span> <span word="the">the</span> <span word="refrigerant">refrigerant</span>, <span word="reducing">reducing</span> <span word="the">the</span> <span word="temperature">temperature</span> <span word="of">of</span> <span word="this">this</span> <span word="second">second</span> <span word="body">body</span> <span word="of">of</span> <span word="air">air</span>. <span word="Of">Of</span> <span word="the">the</span> <span word="two">two</span> <span word="heat">heat</span> <span word="exchangers">exchangers</span>, <span word="one">one</span> <span word="is">is</span> <span word="located">located</span> <span word="inside">inside</span>, <span word="and">and</span> <span word="the">the</span> <span word="other">other</span> <span word="one">one</span> <span word="outside">outside</span> <span word="the">the</span> <span word="house">house</span>, <span word="so">so</span> <span word="each">each</span> <span word="is">is</span> <span word="in">in</span> <span word="contact">contact</span> <span word="with">with</span> <span word="a">a</span> <span word="different">different</span> <span word="body">body</span> <span word="of">of</span> <span word="air">air</span>: <span word="room">room</span> <span word="air">air</span> <span word="and">and</span> <span word="outside">outside</span> <span word="air">air</span>, <span word="respectively">respectively</span>.</p>
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