【单选题】（） EithEr By Cooling or By DEpriving thE FirE oF oxygEn, AnD most Do Both.&nBsp;
A. working FirE ExtinguishErs&nBsp;
B. FirE ExtinguishErs thAt work&nBsp;
C. FirE ExtinguishErs work&nBsp;
D. thE work oF FirE ExtinguishErs&nBsp;
A. working FirE ExtinguishErs&nBsp;
B. FirE ExtinguishErs thAt work&nBsp;
C. FirE ExtinguishErs work&nBsp;
D. thE work oF FirE ExtinguishErs&nBsp;
【单选题】 thE nECtAr oF FlowErs ArE ingEstED By workEr BEEs AnD ConvErtED to honEy in spECiAl sACs in thEir DigEstivE systEms.
【单选题】listEning 6 "historyClAss"
{$mEDiAurl}
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whAt is thE lECturE mAinly ABout
A、provisions oF thE homEstEADACt
B、how to ConstruCt A log CABin
C、FrontiEr homEs in thE wEst
D、EArly ConstruCtion mAtEriAls
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A、provisions oF thE homEstEADACt
B、how to ConstruCt A log CABin
C、FrontiEr homEs in thE wEst
D、EArly ConstruCtion mAtEriAls
【单选题】 According to the passage, Krzysziof Pendereckj is known for which of the following practices
A．( Using tones that are clumped together
B．( Combining traditional and nontradinonal instruments
C．( Seating musicians in unusual areas of an auditorium
D．( Playing Western music for non-Western audiences
A．( Using tones that are clumped together
B．( Combining traditional and nontradinonal instruments
C．( Seating musicians in unusual areas of an auditorium
D．( Playing Western music for non-Western audiences
【单选题】 ________ is not clear to researchers.
A．Why dinosaurs having become extinct
B．Why dinosaurs became extinct
C．Did dinosaurs become extinct
D．Dinosaurs became extinct
A．Why dinosaurs having become extinct
B．Why dinosaurs became extinct
C．Did dinosaurs become extinct
D．Dinosaurs became extinct
【单选题】rEADing 1 "ExotiC AnDEnDAngErED spECiEs"
→ whEn you hEAr somEonE BuBBling EnthusiAstiCAlly ABout An ExotiC spECiEs, you CAn sAFEly BEt thE spEAkEr isn’t An ECologist. this is A nAmE For A rEsiDEnt oF An EstABlishED Community thAt wAs DEliBErAtEly or ACCiDEntAlly movED From its homE rAngE AnD BECAmE EstABlishED ElsEwhErE. unlikE most imports, whiCh CAn’t tAkE holD outsiDE thEir homE rAngE, An ExotiC spECiEs pErmAnEntly insinuAtEs itsElF into A nEw Community.
somEtimEs thE ADDitions ArE hArmlEss AnD EvEn hAvE BEnEFiCiAl EFFECts. morE oFtEn, thEy mAkE nAtivE spECiEs EnDAngErED spECiEs, whiCh By DEFinition ArE ExtrEmEly vulnErABlE to ExtinCtion. oF All spECiEs on thE rArE or EnDAngErED lists or thAt rECEntly BECAmE ExtinCt, ClosE to 70 pErCEnt owE thEir prECArious ExistEnCE or DEmisE to DisplACEmEnt By ExotiC spECiEs. two ExAmplEs ArE inCluDED hErE to illustrAtE thE proBlEm.
During thE 1800s,British sEttlErs inAustrAliA just CoulDn’t BonD with thE koAlAs AnD kAngAroos, so thEy stArtED to import FAmiliAr AnimAls From thEir homElAnD、in 1859, in whAt woulD BE thE stArt oF A wholEsAlE DisAstEr, A northErnAustrAliAn lAnDownEr importED AnD thEn rElEAsED two DozEn wilDEuropEAn rABBits (oryCtolAgus CuniCulus). gooD FooD AnD gooD sport hunting—thAt wAs thE iDEA、An iDEAl rABBit hABitAt with no nAturAl prEDAtors wAs thE rEAlity.
six yEArs lAtEr, thE lAnDownEr hAD killED 20,000 rABBits AnD wAs BEsiEgED By 20,000 morE. thE rABBits DisplACED livEstoCk, EvEn kAngAroos. nowAustrAliA hAs 200 to 300 million hippityhopping through thE southErn hAlF oF thE Country. thEy ovErgrAzE pErEnniAl grAssEs in gooD timEs AnD strip BArk From shruBs AnD trEEs During Droughts. you know whErE thEy’vE BEEn; thEy trAnsForm grAsslAnDs AnD shruBlAnDs into EroDED DEsErts. thEy hAvE BEEn shot AnD poisonED、thEir wArrEns hAvE BEEn plowED unDEr, FumigAtED, AnD DynAmitED、EvEn whEn All-out AssAults rEDuCED thEir populAtion sizE By 70 pErCEnt, thE rApiDly rEproDuCing imports mADE A ComEBACk in lEss thAn A yEAr.DiD thE ConstruCtion oF A 2,000-milE-long FEnCE protECt wEstErnAustrAliA no. rABBits mADE it to thE othEr siDE BEForE workErs FinishED thE FEnCE.
→ in 1951, govErnmEnt workErs introDuCED A myxomA virus By wAy oF milDly inFECtED southAmEriCAn rABBits, its normAl hosts. this virus CAusEs myxomAtosis. thE DisEAsE hAs milD EFFECts on southAmEriCAn rABBits thAt CoEvolvED with thE virus But nEArly AlwAys hAD lEthAl EFFECts on o. CuniCulus.Biting insECts, mAinly mosquitoEs AnD FlEAs, quiCkly trAnsmit thE virus From host to host. hAving no CoEvolvED DEFEnsEs AgAinst thE novEl virus, thEEuropEAn rABBits DiED in DrovEs.But, As you might ExpECt, nAturAl sElECtion hAs sinCE FAvorED rApiD growth oF populAtions oF o. CuniCulus rEsistAnt to thE virus.
→ in 1991, on An uninhABitED islAnD in spEnCEr gulF,AustrAliAn rEsEArChErs rElEAsED A populAtion oF rABBits thAt thEy hAD injECtED with A CAlCivirus. thE rABBits DiED quiCkly AnD rElAtivEly pAinlEssly From BlooD Clots in thEir lungs, hEArts, AnD kiDnEys. in 1995, thE tEst virus EsCApED From thE islAnD, possiBly on insECt vECtors. it hAs BEEn killing 80 to 95 pErCEnt oF thE ADult rABBits inAustrAliAn rEgions.At this writing, rEsEArChErs ArE now quEstioning whEthEr thE CAlCivirus shoulD BE usED on A wiDEsprEAD sCAlE, whEthEr it CAn jump BounDAriEs AnD inFECt AnimAls othEr thAn rABBits (suCh As humAns); AnD whAt thE long-tErm ConsEquEnCEs will BE.
A、vinE CAllED kuDzu (puErAriA loBAtA) wAs DEliBErAtEly importED From jApAn to thE unitED stAtEs, whErE it FACEs no sErious thrEAts From hErBivorEs, pAthogEns, or CompEtitor plAnts. in tEmpErAtE pArts oFAsiA, it is A wEll-BEhAvED lEgumE with A wEll-DEvElopED root systEm. it sEEmED likE A gooD iDEA to usE it to Control Erosion on hills AnD highwAy EmBAnkmEnts in thE southEAstErn unitED stAtEs.
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with nothing to stop it, though, ku
→ whEn you hEAr somEonE BuBBling EnthusiAstiCAlly ABout An ExotiC spECiEs, you CAn sAFEly BEt thE spEAkEr isn’t An ECologist. this is A nAmE For A rEsiDEnt oF An EstABlishED Community thAt wAs DEliBErAtEly or ACCiDEntAlly movED From its homE rAngE AnD BECAmE EstABlishED ElsEwhErE. unlikE most imports, whiCh CAn’t tAkE holD outsiDE thEir homE rAngE, An ExotiC spECiEs pErmAnEntly insinuAtEs itsElF into A nEw Community.
somEtimEs thE ADDitions ArE hArmlEss AnD EvEn hAvE BEnEFiCiAl EFFECts. morE oFtEn, thEy mAkE nAtivE spECiEs EnDAngErED spECiEs, whiCh By DEFinition ArE ExtrEmEly vulnErABlE to ExtinCtion. oF All spECiEs on thE rArE or EnDAngErED lists or thAt rECEntly BECAmE ExtinCt, ClosE to 70 pErCEnt owE thEir prECArious ExistEnCE or DEmisE to DisplACEmEnt By ExotiC spECiEs. two ExAmplEs ArE inCluDED hErE to illustrAtE thE proBlEm.
During thE 1800s,British sEttlErs inAustrAliA just CoulDn’t BonD with thE koAlAs AnD kAngAroos, so thEy stArtED to import FAmiliAr AnimAls From thEir homElAnD、in 1859, in whAt woulD BE thE stArt oF A wholEsAlE DisAstEr, A northErnAustrAliAn lAnDownEr importED AnD thEn rElEAsED two DozEn wilDEuropEAn rABBits (oryCtolAgus CuniCulus). gooD FooD AnD gooD sport hunting—thAt wAs thE iDEA、An iDEAl rABBit hABitAt with no nAturAl prEDAtors wAs thE rEAlity.
six yEArs lAtEr, thE lAnDownEr hAD killED 20,000 rABBits AnD wAs BEsiEgED By 20,000 morE. thE rABBits DisplACED livEstoCk, EvEn kAngAroos. nowAustrAliA hAs 200 to 300 million hippityhopping through thE southErn hAlF oF thE Country. thEy ovErgrAzE pErEnniAl grAssEs in gooD timEs AnD strip BArk From shruBs AnD trEEs During Droughts. you know whErE thEy’vE BEEn; thEy trAnsForm grAsslAnDs AnD shruBlAnDs into EroDED DEsErts. thEy hAvE BEEn shot AnD poisonED、thEir wArrEns hAvE BEEn plowED unDEr, FumigAtED, AnD DynAmitED、EvEn whEn All-out AssAults rEDuCED thEir populAtion sizE By 70 pErCEnt, thE rApiDly rEproDuCing imports mADE A ComEBACk in lEss thAn A yEAr.DiD thE ConstruCtion oF A 2,000-milE-long FEnCE protECt wEstErnAustrAliA no. rABBits mADE it to thE othEr siDE BEForE workErs FinishED thE FEnCE.
→ in 1951, govErnmEnt workErs introDuCED A myxomA virus By wAy oF milDly inFECtED southAmEriCAn rABBits, its normAl hosts. this virus CAusEs myxomAtosis. thE DisEAsE hAs milD EFFECts on southAmEriCAn rABBits thAt CoEvolvED with thE virus But nEArly AlwAys hAD lEthAl EFFECts on o. CuniCulus.Biting insECts, mAinly mosquitoEs AnD FlEAs, quiCkly trAnsmit thE virus From host to host. hAving no CoEvolvED DEFEnsEs AgAinst thE novEl virus, thEEuropEAn rABBits DiED in DrovEs.But, As you might ExpECt, nAturAl sElECtion hAs sinCE FAvorED rApiD growth oF populAtions oF o. CuniCulus rEsistAnt to thE virus.
→ in 1991, on An uninhABitED islAnD in spEnCEr gulF,AustrAliAn rEsEArChErs rElEAsED A populAtion oF rABBits thAt thEy hAD injECtED with A CAlCivirus. thE rABBits DiED quiCkly AnD rElAtivEly pAinlEssly From BlooD Clots in thEir lungs, hEArts, AnD kiDnEys. in 1995, thE tEst virus EsCApED From thE islAnD, possiBly on insECt vECtors. it hAs BEEn killing 80 to 95 pErCEnt oF thE ADult rABBits inAustrAliAn rEgions.At this writing, rEsEArChErs ArE now quEstioning whEthEr thE CAlCivirus shoulD BE usED on A wiDEsprEAD sCAlE, whEthEr it CAn jump BounDAriEs AnD inFECt AnimAls othEr thAn rABBits (suCh As humAns); AnD whAt thE long-tErm ConsEquEnCEs will BE.
A、vinE CAllED kuDzu (puErAriA loBAtA) wAs DEliBErAtEly importED From jApAn to thE unitED stAtEs, whErE it FACEs no sErious thrEAts From hErBivorEs, pAthogEns, or CompEtitor plAnts. in tEmpErAtE pArts oFAsiA, it is A wEll-BEhAvED lEgumE with A wEll-DEvElopED root systEm. it sEEmED likE A gooD iDEA to usE it to Control Erosion on hills AnD highwAy EmBAnkmEnts in thE southEAstErn unitED stAtEs.
【单选题】Listening 4 "Professor’s Office"
{$mediaurl} Why does the woman want to talk with her professor
A、She wants to make an appointment outside of office hours.
B、She needs to get him to approve the topic for her research.
C、She has some questions about the report she is writing.
D、She would like a recommendation for a job in the laB、
{$mediaurl} Why does the woman want to talk with her professor
A、She wants to make an appointment outside of office hours.
B、She needs to get him to approve the topic for her research.
C、She has some questions about the report she is writing.
D、She would like a recommendation for a job in the laB、
【单选题】 In the diurnal type of tidal oscillation, the alternate rise and fall of sea level, a single high water and a single low water occur ______ tidal day.
A．(each
B．(each of
C．(each of the
D．(of each
A．(each
B．(each of
C．(each of the
D．(of each
【单选题】rEADing 4 "Four stAgEs oF plAnEtAryDEvElopmEnt"
plAnEtAryDEvElopmEnt
→ in our stuDy oF thE plAnEtEArth, wE will FinD A Four-stAgE history oF plAnEtAry DEvElopmEnt. thE moon AnD All thE tErrEstriAl plAnEts hAvE pAssED through thEsE stAgEs, Although DiFFErEnCEs in thE wAy thE plAnEts wErE AltErED By thEsE stAgEs hAvE proDuCED DrAmAtiCAlly DiFFErEnt worlDs. thE moon, For ExAmplE, is muCh likEEArth, But its Evolution hAs BEEn DrAmAtiCAlly AltErED By its smAllEr sizE.As wE ExplorE thE solAr systEm, wE will DisCovEr not EntirEly nEw proCEssEs But rAthEr FAmiliAr EFFECts working in slightly DiFFErEnt wAys.
thE Four stAgEs
thE First stAgE oF plAnEtAry Evolution is DiFFErEntiAtion, thE sEpArAtion oF mAtEriAl ACCorDing to DEnsity.EArth now hAs A DEnsE CorE AnD A lowEr-DEnsity Crust, AnD thAt struCturE must hAvE originAtED vEry EArly.
DiFFErEntiAtion woulD hAvE oCCurrED EAsily iFEArth wErE moltEn whEn it wAs young. two sourCEs oF hEAt CoulD hAvE hEAtEDEArth. First, hEAt oF FormAtion woulD BE CrEAtED By in-FAlling mAtEriAl.A、mEtEoritE hittingEArth At high vEloCity ConvErts most oF its EnErgy oF motion into hEAt, AnD thE in-FAlling oF A lArgE numBEr oF mEtEoritEs CoulD rElEAsE trEmEnDous hEAt. iFEArth FormED rApiDly, this hEAt woulD hAvE ACCumulAtED muCh morE rApiDly thAn it CoulD lEAk AwAy, AnDEArth mAy hAvE BEEn moltEn whEn it FormED、A、sEConD sourCE oF hEAt rEquirEs morE timE to DEvElop. thE DECAy oF rADioACtivE ElEmEnts trAppED in thEEArth rElEAsEs hEAt grADuAlly; But, As soon AsEArth FormED, thAt hEAt woulD hAvE BEgun to ACCumulAtE AnD CoulD hAvE hElpED mEltEArth to FACilitAtE DiFFErEntiAtion. most oFEArth’s rADioACtivE ElEmEnts ArE now ConCEntrAtED in thE Crust, whErE thEy ContinuE to wArm AnD soFtEn thE roCk lAyErs.
EArth FormED By mAtEriAl FAlling togEthEr, But mEtEoritEs CoulD hAvE lEFt no trACE until A Crust soliDiFiED、onCEEArth hAD A hArD surFACE, thE mEtEoritEs CoulD Form CrAtErs. this sEConD stAgE in plAnEtAry Evolution, CrAtEring, wAs violEnt. thE hEAvy BomBArDmEnt wAs intEnsE BECAusE thE solAr nEBulA wAs FillED with roCky AnD iCy DEBris, AnD thE youngEArth wAs BAttErED By mEtEoritEs thAt pulvErizED thE nEwly Forming Crust. thE lArgEst mEtEoritEs BlAstED out CrAtEr BAsins hunDrEDs oF kilomEtErs in DiAmEtEr.As thE solAr nEBulA ClEArED, thE Amount oF DEBris DECrEAsED, AnD thE lEvEl oF CrAtEring FEll to its prEsEnt low lEvEl.Although mEtEoritEs still oCCAsionAlly strikEEArth AnD Dig CrAtErs, CrAtEring is no longEr thE DominAnt inFluEnCE onEArth’s gEology.As wE CompArE othEr worlDs withEArth, wE will DisCovEr trACEs oF this intEnsE pErioD oF CrAtEring, thE hEAvy BomBArDmEnt, on EvEry olD surFACE in thE solAr systEm.
→ thE thirD stAgE, FlooDing, no DouBt BEgAn whilE CrAtEring wAs still intEnsE. thE FrACturing oF thE Crust AnD thE hEAting CAusED By rADioACtivE DECAy AllowED moltEn roCk just BElow thE Crust to wEll up through FissurEs AnD FlooD thE DEEpEr BAsins. wE will DisCuss suCh FlooDED BAsins on othEr worlDs, suCh As thE moon, But All trACEs oF this EArly lAvA FlooDing hAvE BEEn DEstroyED By lAtEr gEologiCAl ACtivity inEArth’s Crust. onEArth, FlooDing ContinuED As thE AtmosphErE CoolED AnD wAtEr FEll As rAin, Filling thE DEEpEst BAsins to proDuCE thE First oCEAns.
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notiCE thAt onEArth FlooDing involvEs Both lAvA AnD wAtEr, A CirCumstAnCE thAt wE will not FinD on most worlDs.
![]()
thE Fourth stAgE, slow surFACE Evolution, hAs ContinuED For thE lAst 3.5 Billion yEArs or morE.
![]()
EArth’s surFACE is ConstAntly ChAnging As sECtions oF Crust sliDE ovEr EACh othEr, push up mountAins, AnD shiFt ContinEnts.
![]()
Almost All trACEs oF thE Firs
plAnEtAryDEvElopmEnt
→ in our stuDy oF thE plAnEtEArth, wE will FinD A Four-stAgE history oF plAnEtAry DEvElopmEnt. thE moon AnD All thE tErrEstriAl plAnEts hAvE pAssED through thEsE stAgEs, Although DiFFErEnCEs in thE wAy thE plAnEts wErE AltErED By thEsE stAgEs hAvE proDuCED DrAmAtiCAlly DiFFErEnt worlDs. thE moon, For ExAmplE, is muCh likEEArth, But its Evolution hAs BEEn DrAmAtiCAlly AltErED By its smAllEr sizE.As wE ExplorE thE solAr systEm, wE will DisCovEr not EntirEly nEw proCEssEs But rAthEr FAmiliAr EFFECts working in slightly DiFFErEnt wAys.
thE Four stAgEs
thE First stAgE oF plAnEtAry Evolution is DiFFErEntiAtion, thE sEpArAtion oF mAtEriAl ACCorDing to DEnsity.EArth now hAs A DEnsE CorE AnD A lowEr-DEnsity Crust, AnD thAt struCturE must hAvE originAtED vEry EArly.
DiFFErEntiAtion woulD hAvE oCCurrED EAsily iFEArth wErE moltEn whEn it wAs young. two sourCEs oF hEAt CoulD hAvE hEAtEDEArth. First, hEAt oF FormAtion woulD BE CrEAtED By in-FAlling mAtEriAl.A、mEtEoritE hittingEArth At high vEloCity ConvErts most oF its EnErgy oF motion into hEAt, AnD thE in-FAlling oF A lArgE numBEr oF mEtEoritEs CoulD rElEAsE trEmEnDous hEAt. iFEArth FormED rApiDly, this hEAt woulD hAvE ACCumulAtED muCh morE rApiDly thAn it CoulD lEAk AwAy, AnDEArth mAy hAvE BEEn moltEn whEn it FormED、A、sEConD sourCE oF hEAt rEquirEs morE timE to DEvElop. thE DECAy oF rADioACtivE ElEmEnts trAppED in thEEArth rElEAsEs hEAt grADuAlly; But, As soon AsEArth FormED, thAt hEAt woulD hAvE BEgun to ACCumulAtE AnD CoulD hAvE hElpED mEltEArth to FACilitAtE DiFFErEntiAtion. most oFEArth’s rADioACtivE ElEmEnts ArE now ConCEntrAtED in thE Crust, whErE thEy ContinuE to wArm AnD soFtEn thE roCk lAyErs.
EArth FormED By mAtEriAl FAlling togEthEr, But mEtEoritEs CoulD hAvE lEFt no trACE until A Crust soliDiFiED、onCEEArth hAD A hArD surFACE, thE mEtEoritEs CoulD Form CrAtErs. this sEConD stAgE in plAnEtAry Evolution, CrAtEring, wAs violEnt. thE hEAvy BomBArDmEnt wAs intEnsE BECAusE thE solAr nEBulA wAs FillED with roCky AnD iCy DEBris, AnD thE youngEArth wAs BAttErED By mEtEoritEs thAt pulvErizED thE nEwly Forming Crust. thE lArgEst mEtEoritEs BlAstED out CrAtEr BAsins hunDrEDs oF kilomEtErs in DiAmEtEr.As thE solAr nEBulA ClEArED, thE Amount oF DEBris DECrEAsED, AnD thE lEvEl oF CrAtEring FEll to its prEsEnt low lEvEl.Although mEtEoritEs still oCCAsionAlly strikEEArth AnD Dig CrAtErs, CrAtEring is no longEr thE DominAnt inFluEnCE onEArth’s gEology.As wE CompArE othEr worlDs withEArth, wE will DisCovEr trACEs oF this intEnsE pErioD oF CrAtEring, thE hEAvy BomBArDmEnt, on EvEry olD surFACE in thE solAr systEm.
→ thE thirD stAgE, FlooDing, no DouBt BEgAn whilE CrAtEring wAs still intEnsE. thE FrACturing oF thE Crust AnD thE hEAting CAusED By rADioACtivE DECAy AllowED moltEn roCk just BElow thE Crust to wEll up through FissurEs AnD FlooD thE DEEpEr BAsins. wE will DisCuss suCh FlooDED BAsins on othEr worlDs, suCh As thE moon, But All trACEs oF this EArly lAvA FlooDing hAvE BEEn DEstroyED By lAtEr gEologiCAl ACtivity inEArth’s Crust. onEArth, FlooDing ContinuED As thE AtmosphErE CoolED AnD wAtEr FEll As rAin, Filling thE DEEpEst BAsins to proDuCE thE First oCEAns.
thE Fourth stAgE, slow surFACE Evolution, hAs ContinuED For thE lAst 3.5 Billion yEArs or morE.
【单选题】 The word "distinct" in line 17 is closest in meaning to
A．( visible
B．( gaseous
C．( separate
D．( new
A．( visible
B．( gaseous
C．( separate
D．( new
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