职称英语理工类B级完型填空精选习题(2)
<p> <span word="Scientists">Scientists</span> <span word="say">say</span> <span word="they">they</span> <span word="are">are</span> <span word="beginning">beginning</span> <span word="to">to</span> <span word="learn">learn</span></p><p> <span word="Every">Every</span> <span word="living">living</span> <span word="thing">thing</span> <span word="has">has</span> <span word="what">what</span> <span word="scientists">scientists</span> <span word="call">call</span> <span word="a">a</span> <span word="biological">biological</span> <span word="clock">clock</span> <span word="that">that</span> <span word="controls">controls</span> <span word="behavior">behavior</span>. <span word="The">The</span> <span word="biological">biological</span> <span word="clock">clock</span> <span word="tells">tells</span> __1__ <span word="when">when</span> <span word="to">to</span> <span word="form">form</span> <span word="flowers">flowers</span> <span word="and">and</span> <span word="when">when</span> <span word="the">the</span> <span word="flowers">flowers</span> <span word="should">should</span> <span word="open">open</span>. <span word="It">It</span> <span word="tells">tells</span> __2__ <span word="when">when</span> <span word="to">to</span> <span word="leave">leave</span> <span word="the">the</span> <span word="protective">protective</span> <span word="cocoon">cocoon</span> <span word="and">and</span> <span word="fly">fly</span> <span word="away">away</span>, <span word="and">and</span> <span word="it">it</span> <span word="tells">tells</span> <span word="animals">animals</span> <span word="and">and</span> <span word="human">human</span> <span word="beings">beings</span> <span word="when">when</span> <span word="to">to</span> <span word="eat">eat</span>, <span word="sleep">sleep</span> <span word="and">and</span> <span word="wake">wake</span>.</p><p> <span word="Events">Events</span> <span word="outside">outside</span> <span word="the">the</span> <span word="plant">plant</span> <span word="and">and</span> <span word="animal">animal</span> __3__ <span word="the">the</span> <span word="actions">actions</span> <span word="of">of</span> <span word="some">some</span> <span word="biological">biological</span> <span word="clocks">clocks</span>. <span word="Scientists">Scientists</span> <span word="recently">recently</span> <span word="found">found</span>, <span word="for">for</span> <span word="example">example</span>, <span word="that">that</span> <span word="a">a</span> <span word="tiny">tiny</span> <span word="animal">animal</span> <span word="changes">changes</span> <span word="the">the</span> <span word="color">color</span> <span word="of">of</span> <span word="its">its</span> <span word="fur">fur</span> __4__ <span word="the">the</span> <span word="number">number</span> <span word="of">of</span> <span word="hours">hours</span> <span word="of">of</span> <span word="daylight">daylight</span>. <span word="In">In</span> <span word="the">the</span> <span word="short">short</span> __5__ <span word="of">of</span> <span word="winter">winter</span>, <span word="its">its</span> <span word="fur">fur</span> <span word="becomes">becomes</span> <span word="white">white</span>. <span word="The">The</span> <span word="fur">fur</span> <span word="becomes">becomes</span> <span word="gray">gray</span> <span word="brown">brown</span> <span word="in">in</span> <span word="color">color</span> <span word="in">in</span> <span word="the">the</span> <span word="longer">longer</span> <span word="hours">hours</span> <span word="of">of</span> <span word="daylight">daylight</span> <span word="in">in</span> <span word="summer">summer</span>.</p><p> <span word="Inner">Inner</span> <span word="signals">signals</span> <span word="control">control</span> <span word="other">other</span> <span word="biological">biological</span> <span word="clocks">clocks</span>. <span word="German">German</span> <span word="scientists">scientists</span> <span word="found">found</span> <span word="that">that</span> <span word="some">some</span> <span word="kind">kind</span> <span word="of">of</span> <span word="internal">internal</span> <span word="clock">clock</span> <span word="seems">seems</span> <span word="to">to</span> <span word="order">order</span> <span word="birds">birds</span> <span word="to">to</span> <span word="begin">begin</span> <span word="their">their</span> <span word="long">long</span> <span word="migration">migration</span> __6__ <span word="twice">twice</span> <span word="each">each</span> <span word="year">year</span>. <span word="Birds">Birds</span> __7__ <span word="from">from</span> <span word="flying">flying</span> <span word="become">become</span> <span word="restless">restless</span> <span word="when">when</span> <span word="it">it</span> <span word="is">is</span> <span word="time">time</span> <span word="for">for</span> <span word="the">the</span> <span word="trip">trip</span>, __8__ <span word="they">they</span> <span word="become">become</span> <span word="calm">calm</span> <span word="again">again</span> <span word="when">when</span> <span word="the">the</span> <span word="time">time</span> <span word="of">of</span> <span word="the">the</span> <span word="flight">flight</span> <span word="has">has</span> <span word="ended">ended</span>.</p><p> <span word="Scientists">Scientists</span> <span word="say">say</span> <span word="they">they</span> <span word="are">are</span> <span word="beginning">beginning</span> <span word="to">to</span> <span word="learn">learn</span> which __9__ of the brain contain biological clocks. An American researcher, Martin Moorhead, said a small group of cells near the front of the brain __10__ to control the timing of some of our actions. These __11__ tell a person when to __12__, when to sleep and when to seek food. Scientists say there probably are other biological clock cells that control other body activities.</p>
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