2014年职称英语理工类C级阅读理解精华练习(3)
<p> <span word="Plant">Plant</span> <span word="Gas">Gas</span></p><p> <span word="Scientists">Scientists</span> <span word="have">have</span> <span word="been">been</span> <span word="studying">studying</span> <span word="natural">natural</span> <span word="sources">sources</span> <span word="of">of</span> <span word="methane">methane</span> <span word="for">for</span> <span word="decades">decades</span> <span word="but">but</span> <span word="hadnt">hadnt</span> <span word="regarded">regarded</span> <span word="plants">plants</span> <span word="as">as</span> <span word="a">a</span> <span word="producer">producer</span>，<span word="notes">notes</span> <span word="Frank">Frank</span> <span word="Keppler">Keppler</span>，<span word="a">a</span> <span word="geochem">geochem</span>[<span word="st">st</span> <span word="at">at</span> <span word="the">the</span> <span word="Max">Max</span> <span word="Planck">Planck</span> <span word="Institute">Institute</span> <span word="for">for</span> <span word="Nuclear">Nuclear</span> <span word="Physics">Physics</span> <span word="in">in</span> <span word="Heidelberg">Heidelberg</span>，<span word="Germany">Germany</span>1.<span word="Now">Now</span> <span word="Keppler">Keppler</span> <span word="and">and</span> <span word="his">his</span> <span word="colleagues">colleagues</span> <span word="find">find</span> <span word="that">that</span> <span word="plants">plants</span>，<span word="from">from</span> <span word="grasses">grasses</span> <span word="to">to</span> <span word="trees">trees</span>，<span word="may">may</span> <span word="also">also</span> <span word="be">be</span> <span word="sources">sources</span> <span word="of">of</span> <span word="the">the</span> <span word="greenhouse">greenhouse</span> <span word="gas">gas</span>.<span word="This">This</span> <span word="is">is</span> <span word="really">really</span> <span word="surprising">surprising</span>，<span word="because">because</span> <span word="most">most</span> <span word="scientists">scientists</span> <span word="assumed">assumed</span> <span word="that">that</span> <span word="methane">methane</span> <span word="production">production</span> <span word="requires">requires</span> <span word="an">an</span> <span word="oxygen">oxygen</span>-<span word="free">free</span> <span word="environment">environment</span>.</p><p> <span word="Previously">Previously</span>，<span word="researchers">researchers</span> <span word="had">had</span> <span word="thought">thought</span> <span word="that">that</span> <span word="it">it</span> <span word="was">was</span> <span word="impossible">impossible</span> <span word="for">for</span> <span word="plants">plants</span> <span word="to">to</span> <span word="make">make</span> <span word="significant">significant</span> <span word="amounts">amounts</span> <span word="of">of</span> <span word="the">the</span> <span word="gas">gas</span>.<span word="They">They</span> <span word="had">had</span> <span word="assumed">assumed</span> <span word="that">that</span>，<span word="microbes">microbes</span>2 <span word="need">need</span> <span word="to">to</span> <span word="be">be</span> <span word="in">in</span> <span word="environments">environments</span> <span word="without">without</span> <span word="oxygen">oxygen</span> <span word="to">to</span> <span word="produce">produce</span> <span word="methane">methane</span>.<span word="Methane">Methane</span> <span word="is">is</span> <span word="a">a</span> <span word="greenhouse">greenhouse</span> <span word="gas">gas</span>，<span word="like">like</span> <span word="carbon">carbon</span> <span word="dioxide">dioxide</span>.<span word="Gases">Gases</span> <span word="such">such</span> <span word="as">as</span> <span word="methane">methane</span> <span word="and">and</span> <span word="carbon">carbon</span> <span word="dioxide">dioxide</span> <span word="trap">trap</span> <span word="heat">heat</span> <span word="in">in</span> <span word="Earths">Earths</span> <span word="atmosphere">atmosphere</span> <span word="and">and</span> <span word="contributeto">contributeto</span> <span word="global">global</span> <span word="warming">warming</span>.</p><p> <span word="In">In</span> <span word="its">its</span> <span word="experiments">experiments</span>，<span word="Kepplers">Kepplers</span> <span word="team">team</span> <span word="used">used</span> <span word="sealed">sealed</span> <span word="chambers">chambers</span> <span word="that">that</span> <span word="contained">contained</span> <span word="the">the</span> <span word="same">same</span> <span word="concentration">concentration</span> <span word="of">of</span> <span word="oxygen">oxygen</span> <span word="that">that</span> <span word="Earths">Earths</span> <span word="atmosphere">atmosphere</span> <span word="has">has</span>.<span word="They">They</span> <span word="measured">measured</span> <span word="the">the</span> <span word="amounts">amounts</span> <span word="of">of</span> <span word="methane">methane</span> <span word="that">that</span> <span word="were">were</span> <span word="released">released</span> <span word="by">by</span> <span word="both">both</span> <span word="living">living</span> <span word="plants">plants</span>;<span word="and">and</span> <span word="dried">dried</span> <span word="plant">plant</span> <span word="material">material</span>，<span word="such">such</span> <span word="as">as</span> <span word="fallen">fallen</span> <span word="leaves">leaves</span>.</p><p> <span word="With">With</span> <span word="the">the</span> <span word="dried">dried</span> <span word="plants">plants</span>，<span word="the">the</span> <span word="researchers">researchers</span> <span word="took">took</span> <span word="measurement">measurement</span> <span word="at">at</span> <span word="temperatures">temperatures</span> <span word="ranging">ranging</span> <span word="from">from</span> 30 <span word="degrees">degrees</span> <span word="Celsius">Celsius</span> <span word="to">to</span> 70 <span word="degrees">degrees</span> <span word="C">C</span>.<span word="At">At</span> 30 <span word="degrees">degrees</span> <span word="C">C</span>，<span word="they">they</span> <span word="found">found</span>，<span word="a">a</span> <span word="gram">gram</span> <span word="of">of</span> <span word="dried">dried</span> <span word="plant">plant</span> <span word="material">material</span> <span word="released">released</span> <span word="up">up</span> <span word="to">to</span> 3 <span word="nanograms">nanograms</span> <span word="of">of</span> <span word="methane">methane</span> <span word="per">per</span> <span word="hour">hour</span>. <span word="With">With</span> <span word="every">every</span> 10-<span word="degree">degree</span> <span word="rise">rise</span> <span word="in">in</span> <span word="temperature">temperature</span>，<span word="the">the</span> <span word="amount">amount</span> <span word="of">of</span> <span word="methane">methane</span> <span word="released">released</span> <span word="each">each</span> <span word="hour">hour</span> <span word="roughly">roughly</span> <span word="doubled">doubled</span>.</p>
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