2013年GMAT考试阅读理解模拟试题(4)
<p> <span word="In">In</span> <span word="terrestrial">terrestrial</span> <span word="environments">environments</span>, <span word="gravity">gravity</span> <span word="places">places</span> <span word="special">special</span> <span word="demands">demands</span> <span word="on">on</span> <span word="the">the</span> <span word="cardiovascular">cardiovascular</span> <span word="systems">systems</span> <span word="of">of</span> <span word="animals">animals</span>. <span word="Gravitational">Gravitational</span> <span word="pressure">pressure</span> <span word="can">can</span> <span word="cause">cause</span> <span word="blood">blood</span> <span word="to">to</span> <span word="pool">pool</span> <span word="in">in</span> <span word="the">the</span> <span word="lower">lower</span> <span word="regions">regions</span> <span word="of">of</span> <span word="the">the</span> <span word="body">body</span>, <span word="making">making</span> <span word="it">it</span> <span word="difficult">difficult</span> <span word="to">to</span> <span word="circulate">circulate</span> <span word="blood">blood</span> <span word="to">to</span> <span word="critical">critical</span> <span word="organs">organs</span> <span word="such">such</span> <span word="as">as</span> <span word="the">the</span> <span word="brain">brain</span>. <span word="Terrestrial">Terrestrial</span> <span word="snakes">snakes</span>, <span word="in">in</span> <span word="particular">particular</span>, <span word="exhibit">exhibit</span> <span word="adaptations">adaptations</span> <span word="that">that</span> <span word="aid">aid</span> <span word="in">in</span> <span word="circulating">circulating</span> <span word="blood">blood</span> <span word="against">against</span> <span word="the">the</span> <span word="force">force</span> <span word="of">of</span> <span word="gravity">gravity</span>.</p><p> <span word="The">The</span> <span word="problem">problem</span> <span word="confronting">confronting</span> <span word="terrestrial">terrestrial</span> <span word="snakes">snakes</span> <span word="is">is</span> <span word="best">best</span> <span word="illustrated">illustrated</span> <span word="by">by</span> <span word="what">what</span> <span word="happens">happens</span> <span word="to">to</span> <span word="sea">sea</span> <span word="snakes">snakes</span> <span word="when">when</span> <span word="removed">removed</span> <span word="from">from</span> <span word="their">their</span> <span word="supportive">supportive</span> <span word="medium">medium</span>. <span word="Because">Because</span> <span word="the">the</span> <span word="vertical">vertical</span> <span word="pressure">pressure</span> <span word="gradients">gradients</span> <span word="within">within</span> <span word="the">the</span> <span word="blood">blood</span> <span word="vessels">vessels</span> <span word="are">are</span> <span word="counteracted">counteracted</span> <span word="by">by</span> <span word="similar">similar</span> <span word="pressure">pressure</span> <span word="gradients">gradients</span> <span word="in">in</span> <span word="the">the</span> <span word="surrounding">surrounding</span> <span word="water">water</span>, <span word="the">the</span> <span word="distribution">distribution</span> <span word="of">of</span> <span word="blood">blood</span> <span word="throughout">throughout</span> <span word="the">the</span> <span word="body">body</span> <span word="of">of</span> <span word="sea">sea</span> <span word="snakes">snakes</span> <span word="remains">remains</span> <span word="about">about</span> <span word="the">the</span> <span word="same">same</span> <span word="regardless">regardless</span> <span word="of">of</span> <span word="their">their</span> <span word="orientation">orientation</span> <span word="in">in</span> <span word="space">space</span>, <span word="provided">provided</span> <span word="they">they</span> <span word="remain">remain</span> <span word="in">in</span> <span word="the">the</span> <span word="ocean">ocean</span>. <span word="When">When</span> <span word="removed">removed</span> <span word="from">from</span> <span word="the">the</span> <span word="water">water</span> <span word="and">and</span> <span word="tilted">tilted</span> <span word="at">at</span> <span word="various">various</span> <span word="angles">angles</span> <span word="with">with</span> <span word="the">the</span> <span word="head">head</span> <span word="up">up</span>, <span word="however">however</span>, <span word="blood">blood</span> <span word="pressure">pressure</span> <span word="at">at</span> <span word="their">their</span> <span word="midpoint">midpoint</span> <span word="drops">drops</span> <span word="significantly">significantly</span>, <span word="and">and</span> <span word="at">at</span> <span word="brain">brain</span> <span word="level">level</span> <span word="falls">falls</span> <span word="to">to</span> <span word="zero">zero</span>. <span word="That">That</span> <span word="many">many</span> <span word="terrestrial">terrestrial</span> <span word="snakes">snakes</span> <span word="in">in</span> <span word="similar">similar</span> <span word="spatial">spatial</span> <span word="orientations">orientations</span> <span word="do">do</span> <span word="not">not</span> <span word="experience">experience</span> <span word="this">this</span> <span word="kind">kind</span> <span word="of">of</span> <span word="circulatory">circulatory</span> <span word="failure">failure</span> <span word="suggests">suggests</span> <span word="that">that</span> <span word="certain">certain</span> <span word="adaptations">adaptations</span> <span word="enable">enable</span> <span word="them">them</span> <span word="to">to</span> <span word="regulate">regulate</span> <span word="blood">blood</span> <span word="pressure">pressure</span> <span word="more">more</span> <span word="effectively">effectively</span> <span word="in">in</span> <span word="those">those</span> <span word="orientations">orientations</span>.</p><p> <span word="One">One</span> <span word="such">such</span> <span word="adaptation">adaptation</span> <span word="is">is</span> <span word="the">the</span> <span word="closer">closer</span> <span word="proximity">proximity</span> <span word="of">of</span> <span word="the">the</span> <span word="terrestrial">terrestrial</span> <span word="snake">snake</span>\'<span word="s">s</span> <span word="heart">heart</span> <span word="to">to</span> <span word="its">its</span> <span word="head">head</span>, <span word="which">which</span> <span word="helps">helps</span> <span word="to">to</span> <span word="ensure">ensure</span> <span word="circulation">circulation</span> <span word="to">to</span> <span word="the">the</span> <span word="brain">brain</span>, <span word="regardless">regardless</span> <span word="of">of</span> <span word="the">the</span> <span word="snake">snake</span>\'<span word="s">s</span> <span word="orientation">orientation</span> <span word="in">in</span> <span word="space">space</span>. <span word="The">The</span> <span word="heart">heart</span> <span word="of">of</span> <span word="sea">sea</span> <span word="snakes">snakes</span> <span word="can">can</span> <span word="be">be</span> <span word="located">located</span> <span word="near">near</span> <span word="the">the</span> <span word="middle">middle</span> <span word="of">of</span> <span word="the">the</span> <span word="body">body</span>, <span word="a">a</span> <span word="position">position</span> <span word="that">that</span> <span word="minimizes">minimizes</span> <span word="the">the</span> <span word="work">work</span> <span word="entailed">entailed</span> <span word="in">in</span> <span word="circulating">circulating</span> <span word="blood">blood</span> <span word="to">to</span> <span word="both">both</span> <span word="extremities">extremities</span>. <span word="In">In</span> <span word="arboreal">arboreal</span> <span word="snakes">snakes</span>, <span word="however">however</span>, <span word="which">which</span> <span word="dwell">dwell</span> <span word="in">in</span> <span word="trees">trees</span> <span word="and">and</span> <span word="often">often</span> <span word="assume">assume</span> <span word="a">a</span> <span word="vertical">vertical</span> <span word="posture">posture</span>, <span word="the">the</span> <span word="average">average</span> <span word="distance">distance</span> <span word="from">from</span> <span word="the">the</span> <span word="heart">heart</span> <span word="to">to</span> <span word="the">the</span> <span word="head">head</span> <span word="can">can</span> <span word="be">be</span> <span word="as">as</span> <span word="little">little</span> <span word="as">as</span> 15 <span word="percent">percent</span> <span word="of">of</span> <span word="overall">overall</span> <span word="body">body</span> <span word="length">length</span>. <span word="Such">Such</span> <span word="a">a</span> <span word="location">location</span> <span word="requires">requires</span> <span word="that">that</span> <span word="blood">blood</span> <span word="circulated">circulated</span> <span word="to">to</span> <span word="the">the</span> <span word="tail">tail</span> <span word="of">of</span> <span word="the">the</span> <span word="snake">snake</span> <span word="travel">travel</span> <span word="a">a</span> <span word="greater">greater</span> <span word="distance">distance</span> <span word="back">back</span> <span word="to">to</span> <span word="the">the</span> <span word="heart">heart</span>, <span word="a">a</span> <span word="problem">problem</span> <span word="solved">solved</span> <span word="by">by</span> <span word="another">another</span> <span word="adaptation">adaptation</span>. <span word="When">When</span> <span word="climbing">climbing</span>, <span word="arboreal">arboreal</span> <span word="snakes">snakes</span> <span word="often">often</span> <span word="pause">pause</span> <span word="momentarily">momentarily</span> <span word="to">to</span> <span word="wiggle">wiggle</span> <span word="their">their</span> <span word="bodies">bodies</span>, <span word="causing">causing</span> <span word="waves">waves</span> <span word="of">of</span> <span word="muscle">muscle</span> <span word="contraction">contraction</span> <span word="that">that</span> <span word="advance">advance</span> <span word="from">from</span> <span word="the">the</span> <span word="lower">lower</span> <span word="torso">torso</span> <span word="to">to</span> <span word="head">head</span>. <span word="By">By</span> <span word="compressing">compressing</span> <span word="the">the</span> <span word="veins">veins</span> <span word="and">and</span> <span word="forcing">forcing</span> <span word="blood">blood</span> <span word="forward">forward</span>, <span word="these">these</span> <span word="contractions">contractions</span> <span word="apparently">apparently</span> <span word="improve">improve</span> <span word="the">the</span> <span word="flow">flow</span> <span word="of">of</span> <span word="venous">venous</span> <span word="blood">blood</span> <span word="returning">returning</span> <span word="to">to</span> <span word="the">the</span> <span word="heart">heart</span>.</p>
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