meili 发表于 2022-10-18 19:11:17

gre考试阅读真题解析(B)

<p>  <span word="The">The</span> <span word="defoliation">defoliation</span> <span word="of">of</span> <span word="millions">millions</span> <span word="of">of</span> <span word="acres">acres</span> <span word="of">of</span> <span word="trees">trees</span> <span word="by">by</span> <span word="massive">massive</span> <span word="infestations">infestations</span> <span word="of">of</span> <span word="gypsy">gypsy</span> <span word="moth">moth</span> <span word="caterpillars">caterpillars</span> <span word="is">is</span> <span word="a">a</span> <span word="recurring">recurring</span> <span word="phenomenon">phenomenon</span> <span word="in">in</span> <span word="the">the</span> <span word="northeastern">northeastern</span> <span word="United">United</span> <span word="States">States</span>. <span word="In">In</span> <span word="studying">studying</span> <span word="these">these</span> <span word="outbreaks">outbreaks</span>, <span word="scientists">scientists</span> <span word="have">have</span> <span word="discovered">discovered</span> <span word="that">that</span> <span word="affected">affected</span> <span word="trees">trees</span> <span word="fight">fight</span> <span word="back">back</span> <span word="by">by</span> <span word="releasing">releasing</span> <span word="toxic">toxic</span> <span word="chemicals">chemicals</span>, <span word="mainly">mainly</span> <span word="phenols">phenols</span>, <span word="into">into</span> <span word="their">their</span> <span word="foliage">foliage</span>. <span word="These">These</span> <span word="noxious">noxious</span> <span word="substances">substances</span> <span word="limit">limit</span> <span word="caterpillars">caterpillars</span> <span word="growth">growth</span> <span word="and">and</span> <span word="reduce">reduce</span> <span word="the">the</span> <span word="number">number</span> <span word="of">of</span> <span word="eggs">eggs</span> <span word="that">that</span> <span word="female">female</span> <span word="moths">moths</span> <span word="lay">lay</span>. <span word="Phenols">Phenols</span> <span word="also">also</span> <span word="make">make</span> <span word="the">the</span> <span word="eggs">eggs</span> <span word="smaller">smaller</span>, <span word="which">which</span> <span word="reduces">reduces</span> <span word="the">the</span> <span word="growth">growth</span> <span word="of">of</span> <span word="the">the</span> <span word="following">following</span> <span word="years">years</span> <span word="caterpillars">caterpillars</span>. <span word="Because">Because</span> <span word="the">the</span> <span word="number">number</span> <span word="of">of</span> <span word="eggs">eggs</span> <span word="a">a</span> <span word="female">female</span> <span word="moth">moth</span> <span word="produces">produces</span> <span word="is">is</span> <span word="directly">directly</span> <span word="related">related</span> <span word="to">to</span> <span word="her">her</span> <span word="size">size</span>, <span word="and">and</span> <span word="because">because</span> <span word="her">her</span> <span word="size">size</span> <span word="is">is</span> <span word="determined">determined</span> <span word="entirely">entirely</span> <span word="by">by</span> <span word="her">her</span> <span word="feeding">feeding</span> <span word="success">success</span> <span word="as">as</span> <span word="a">a</span> <span word="caterpillar">caterpillar</span>, <span word="the">the</span> <span word="trees">trees</span> <span word="defensive">defensive</span> <span word="mechanism">mechanism</span> <span word="has">has</span> <span word="an">an</span> <span word="impact">impact</span> <span word="on">on</span> <span word="moth">moth</span> <span word="fecundity">fecundity</span>.</p><p>  <span word="The">The</span> <span word="gypsy">gypsy</span> <span word="moth">moth</span> <span word="is">is</span> <span word="also">also</span> <span word="subject">subject</span> <span word="to">to</span> <span word="attack">attack</span> <span word="by">by</span> <span word="the">the</span> <span word="nucleopolyhedrosis">nucleopolyhedrosis</span> <span word="virus">virus</span>, <span word="or">or</span> <span word="wilt">wilt</span> <span word="disease">disease</span> , <span word="a">a</span> <span word="particularly">particularly</span> <span word="important">important</span> <span word="killer">killer</span> <span word="of">of</span> <span word="the">the</span> <span word="caterpillars">caterpillars</span> <span word="in">in</span> <span word="outbreak">outbreak</span> <span word="years">years</span>. <span word="Caterpillars">Caterpillars</span> <span word="contract">contract</span> <span word="wilt">wilt</span> <span word="disease">disease</span> <span word="when">when</span> <span word="they">they</span> <span word="eat">eat</span> <span word="a">a</span> <span word="leaf">leaf</span> <span word="to">to</span> <span word="which">which</span> <span word="the">the</span> <span word="virus">virus</span>, <span word="encased">encased</span> <span word="in">in</span> <span word="a">a</span> <span word="protein">protein</span> <span word="globule">globule</span>, <span word="has">has</span> <span word="become">become</span> <span word="attached">attached</span>. <span word="Once">Once</span> <span word="ingested">ingested</span> <span word="by">by</span> <span word="a">a</span> <span word="caterpillar">caterpillar</span>, <span word="the">the</span> <span word="protein">protein</span> <span word="globule">globule</span> <span word="dissolves">dissolves</span>, <span word="releasing">releasing</span> <span word="thousands">thousands</span> <span word="of">of</span> <span word="viruses">viruses</span>, <span word="or">or</span> <span word="virions">virions</span>, <span word="that">that</span> <span word="after">after</span> <span word="about">about</span> <span word="two">two</span> <span word="weeks">weeks</span> <span word="multiply">multiply</span> <span word="enough">enough</span> <span word="to">to</span> <span word="fill">fill</span> <span word="the">the</span> <span word="entire">entire</span> <span word="body">body</span> <span word="cavity">cavity</span>. <span word="When">When</span> <span word="the">the</span> <span word="caterpillar">caterpillar</span> <span word="dies">dies</span>, <span word="the">the</span> <span word="virions">virions</span> <span word="are">are</span> <span word="released">released</span> <span word="to">to</span> <span word="the">the</span> <span word="outside">outside</span>, <span word="encased">encased</span> <span word="in">in</span> <span word="a">a</span> <span word="new">new</span> <span word="protein">protein</span> <span word="globule">globule</span> <span word="synthesized">synthesized</span> <span word="from">from</span> <span word="the">the</span> <span word="caterpillars">caterpillars</span> <span word="tissues">tissues</span> <span word="and">and</span> <span word="ready">ready</span> <span word="to">to</span> <span word="be">be</span> <span word="picked">picked</span> <span word="up">up</span> <span word="by">by</span> <span word="other">other</span> <span word="caterpillars">caterpillars</span>.</p><p>  <span word="Knowing">Knowing</span> <span word="that">that</span> <span word="phenols">phenols</span>, <span word="including">including</span> <span word="tannins">tannins</span>, <span word="often">often</span> <span word="act">act</span> <span word="by">by</span> <span word="associating">associating</span> <span word="with">with</span> <span word="and">and</span> <span word="altering">altering</span> <span word="the">the</span> <span word="activity">activity</span> <span word="of">of</span> <span word="proteins">proteins</span>, <span word="researchers">researchers</span> <span word="focused">focused</span> <span word="on">on</span> <span word="the">the</span> <span word="effects">effects</span> <span word="on">on</span> <span word="caterpillars">caterpillars</span> <span word="of">of</span> <span word="ingesting">ingesting</span> <span word="the">the</span> <span word="virus">virus</span> <span word="and">and</span> <span word="leaves">leaves</span> <span word="together">together</span>. <span word="They">They</span> <span word="found">found</span> <span word="that">that</span> <span word="on">on</span> <span word="tannin">tannin</span>-<span word="rich">rich</span> <span word="oak">oak</span> <span word="leaves">leaves</span>, <span word="the">the</span> <span word="virus">virus</span> <span word="is">is</span> <span word="considerably">considerably</span> <span word="less">less</span> <span word="effective">effective</span> <span word="at">at</span> <span word="killing">killing</span> <span word="caterpillars">caterpillars</span> <span word="than">than</span> <span word="when">when</span> <span word="it">it</span> <span word="is">is</span> <span word="on">on</span> <span word="aspen">aspen</span> <span word="leaves">leaves</span>, <span word="which">which</span> <span word="are">are</span> <span word="lower">lower</span> <span word="in">in</span> <span word="phenols">phenols</span>. <span word="In">In</span> <span word="general">general</span>, <span word="the">the</span> <span word="more">more</span> <span word="concentrated">concentrated</span> <span word="the">the</span> <span word="phenols">phenols</span> <span word="in">in</span> <span word="tree">tree</span> <span word="leaves">leaves</span>, <span word="the">the</span> <span word="less">less</span> <span word="deadly">deadly</span> <span word="the">the</span> <span word="virus">virus</span>. <span word="Thus">Thus</span>, <span word="while">while</span> <span word="highly">highly</span> <span word="concentrated">concentrated</span> <span word="phenols">phenols</span> <span word="in">in</span> <span word="tree">tree</span> <span word="leaves">leaves</span> <span word="reduce">reduce</span> <span word="the">the</span> <span word="caterpillar">caterpillar</span> <span word="population">population</span> <span word="by">by</span> <span word="limiting">limiting</span> <span word="the">the</span> <span word="size">size</span> <span word="of">of</span> <span word="caterpillars">caterpillars</span> <span word="and">and</span>, <span word="consequently">consequently</span>, <span word="the">the</span> <span word="size">size</span> <span word="of">of</span> <span word="the">the</span> <span word="females">females</span> <span word="egg">egg</span> <span word="cluster">cluster</span>, <span word="these">these</span> <span word="same">same</span> <span word="chemicals">chemicals</span> <span word="also">also</span> <span word="help">help</span> <span word="caterpillars">caterpillars</span> <span word="survive">survive</span> <span word="by">by</span> <span word="disabling">disabling</span> <span word="the">the</span> <span word="wilt">wilt</span> <span word="virus">virus</span>. <span word="Forest">Forest</span> <span word="stands">stands</span> <span word="of">of</span> <span word="red">red</span> <span word="oaks">oaks</span>, <span word="with">with</span> <span word="their">their</span> <span word="tannin">tannin</span>-<span word="rich">rich</span> <span word="foliage">foliage</span>, <span word="may">may</span> <span word="even">even</span> <span word="provide">provide</span> <span word="caterpillars">caterpillars</span> <span word="with">with</span> <span word="safe">safe</span> <span word="havens">havens</span> <span word="from">from</span> <span word="disease">disease</span>. <span word="In">In</span> <span word="stands">stands</span> <span word="dominated">dominated</span> <span word="by">by</span> <span word="trees">trees</span> <span word="such">such</span> <span word="as">as</span> <span word="aspen">aspen</span>, <span word="however">however</span>, <span word="incipient">incipient</span> <span word="gypsy">gypsy</span> <span word="moth">moth</span> <span word="outbreaks">outbreaks</span> <span word="are">are</span> <span word="quickly">quickly</span> <span word="suppressed">suppressed</span> <span word="by">by</span> <span word="viral">viral</span> <span word="epidemics">epidemics</span>.</p>
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