懂你英语l4u.docx
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懂你英语l4u.docx
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懂你英语l4u
懂你英语L4-Unit21ExtinctionEvents
Level4Unit21Listening?
ExtinctionEvents
TheEarthwasformedabout4.6billionyearsago.Thefirstlifeappearedaboutabillionyearslater.Thefirstplantsdidn'tappearuntilaround2billionyearsago.Untilabout580millionyearsago,lifeformsweresmallandmicroscopic.Sincethattime,lifehasevolvedintomanydifferenttypes,orspecies.However,scientistsestimatethatmorethan99%ofthemarenowextinct.
TherehavebeenseveralextinctioneventsinthehistoryoftheEarth.Inanextinctioneventmanylifeforms,orspeciesoflife,dieout.Thecausesofmassextinctioneventsareunsolvedmysteries.Theseeventsarenotpredictableandcanhappenatanytime.Scientiststhinkthatsomeofthemwerestartedbyasteroidimpactsorvolcaniceruptions.Eventslikethesecanchangetheglobalconditionsthatlifedependson.
Onemajorextinctioneventhappenedabout66millionyearsago.ThateventmayhavebeenstartedbyalargeasteroidthathittheEarth.Asaresult,thedinosaursandabouthalfofallspeciesontheplanetdiedout.Whentheasteroidhittheearth,itstartedachainofevents.Achainofeventsisaseriesofeventslinkedtogether,likeachain.
Thisparticularchainofeventshappenedoveraperiodofmonthsandyears.WhentheasteroidhittheEarth,itcausedahugecloudofdusttoentertheatmosphere.ThiscloudofdustblockedthesunanddarkenedtheEarthformanymonths.Withoutenoughsunlight,plantsandplant-eatinganimalsquicklydied.Withthedeathsofsomanyplantsandanimals,thefoodchaincollapsed.Thisledtothedeathsofmanymorespecies.
Massextinctioneventshaveplayedanimportantpartintheevolutionoflife.Infact,someextinctioneventshavehelpedtoaccelerateevolution.Forexample,somemammalslivedthroughtheageofthedinosaurs,buttheycouldn'tcompete.Whenthedinosaurswereremoved,themammalswereabletocompetemoresuccessfully.Oncetheycouldcompete,mammalsevolvedtoahigherstate.Withoutextinctionevents,perhapswewouldn'tbeheretoday.
Scientistsestimatethattherehavebeenatleast5massextinctionsinthelast540millionyears.Theyalsobelievethatwehaveenteredanewextinctionevent.Speciesarebecomingextinctatamuchfasterratethanbefore.Insteadofasteroidsorvolcaniceruptions,thecurrenteventistheresultofhumanactivities.Humanactivities,forexample,haveledtoglobalwarming.
Globalwarmingistheresultofanincreaseincarbongasesinouratmosphere.Thesegasestrapheatfromthesun,sotheEarthisgettingwarmer.Asaresult,sealevelsarerisingandweatherpatternsarechanging.Inaddition,wehumansaredestroyingthehabitatsofmanyplantsandanimals.Cuttingdownforestsandpollutingriversdestroysthehabitatsofmanyformsoflife.
Thereisnolongeranydoubtthatthisishappening.Speciesoflifearedisappearingatanincreasingrate.Globaltemperaturesarerisingandweatherpatternsarechanging.Scientistsarewarningusthatfastactionisnecessarytosaveourfuture.Ifwedon'tact,wemaygothewayofthedinosaurs.(Thisnewextinctioneventiscausedbyhumans.)
Level4Unit21Vocabulary
BodySystems
Thebody'scirculatorysystemincludestheheartandbloodvessels.Theheartpumpsbloodtoallpartsofthebodythroughanetworkofarteriesandveins.(Thebloodvesselsthatcarryoxygen-richbloodfromtheheartarecalledarteries.)
Thedigestivesystembreaksdownandabsorbsfoodintothebody.It'ssuppliestheenergythatthebodyneedsforgrowthandrepair.Afterdigestion,excessfoodisturnedintowasteandeliminatedfromthebody.(Thedigestivesystemiswherefoodisbrokendownandabsorbedintothebody.)
Thenervoussystemincludesthebrain,spinalcordandnerves.Thisisyourbody'scontrolsystem.Itcontrolsyourmusclesandorgans,includingyourcirculatoryanddigestivesystem.(Thenervoussystemregulatesyourheartbeatanddigestion.)
Therespiratorysystemincludesthenoseandlungs.Itbringsairandoxygenintothebodyandremovescarbondioxide.Thelungsarewhereoxygenentersthebloodstream,andcarbondioxideisremoved.
Theimmunesystemprotectsthebodyagainstinfectionsanddiseases.Sneezingandfeverareexamplesofhowtheimmunesystemworks.Ifaninfectioninvadesthebody,theimmunesystemattacksit.
GreatDiscoveries
Thecontrolleduseoffireallowedpeopletocookfoodandsurviveinthecolderclimates.Fireprovidedlightsothatpeoplecouldworkandsocializeforlongerhours.
Withtheinventionofagriculture,peoplecouldgrowfoodandsettleintocommunities.Bygrowingfood,peoplecouldspendlesstimehunting,andmoretimeforotherthingssuchasart.(Withthedevelopmentofagriculture,peoplehadmoretimeforotheractivities.)
Thedomesticationofanimalsallowedpeopletoraiseanduseanimalsforfoodandwork.Byraisingherdsofanimalssuchassheep,humanshadaregularsupplyofmeatandclothing.Thestrengthofanimalssuchashorsesandoxenwasusedforworkandtransportation.
Thedevelopmentoftoolsandmachineshasresultedinmoreefficient?
manufacturingandconstruction.Withbettertoolsandmachines,workcanbedonewithfewerpeopleandatmuchlowercosts.(Theuseofmachineshasreducedthenumberofpeopleneededtomakethings.)
Thedevelopmentofscienceandengineeringhasimprovedmanythings,includingcommunications.Withanunderstandingofelectricity,telephonesandradiosallowpeopletocommunicateoverlongdistances.(Scienceandengineeringhavechangedthewaywecommunicatewitheachother.)
Level4Unit2Part1Dialogue
SmartphoneAddiction
Itookavacationlastnight.
Whatareyoutalkingabout?
Wheredidyoutakeyourvacation?
Ididn'tgoanywhere.
Ijustspendaneveningwithoutmysmartphone.
Howwasit?
Itwasgreat.Igotarealmagazineandreaditwithnointerruption.
Itwasverypeaceful.
Yes,Ihaven'tdonethatinalongtime.
Youknowwhat?
I'mbeginningtohatesmartphones.
Really?
butyoucan'tlivewithoutone,right?
Yes,that'stheproblem.
Thesethingsarechangingthewaypeoplelive.
Yes,Ijustsawadocumentaryaboutthat.
Ahusbandwascomplainingtohiswifethatshewasspendingtoomuchtimeonhersmartphone.
whathappened?
Didtheygetadivorce?
Youguessedit.Intheend,theygotadivorce.
It'sabitironic,don'tyouthink?
Smartphoneweresupposedtobringpeopletogether,buttheyarepullingpeopleapart.
Yes,youareright.
Hey,justaminute.I'vegotamessageonmysmartphone,anditcan'twait.
RudeBoss
Hey,wakeupandgetbacktowork.
What'swrongwithyou?
I'monmybreaksir,andIhaveabadheadache.
Well,wearenotpayingyoutosleep.
Ifyou'regoingtosleep,sleepsomeplaceelse.
Yes,sir,sorry,itwon'thappenagain.
Ithadbetternot.
Justaminute.
Don'ttalktomelikethat.
Whatdidyousay?
Youhurtme.youdon'thavetotreatpeoplelikethat.
Well,ifyoudon'tlikeit,Isuggestyouleave.
OK,Iwill.I'vehadenoughofyou.
I'llgetajobsomewhereelse.
(Themanagertreatstheemployeesinathreateningmanner.)
(Theemployeetreatsthemanagerrespectfully.)
懂你英语L4-Unit22?
Point?
of?
view
Level4Unit2Part2Listening
Pointofview
Thismanisholdingapieceoffruitinhishand.Thepieceoffruitiseitheranorangeoranapple.Wecan’tseewhichitisbecausewecan’tseeinsidethebox.Theprobabilitythatitisanorangeisequaltotheprobabilitythatitisanapple.Itmaybeanapple,anditmaybeanorange.It’sgottobeoneortheother.Itcan’tbeanythingelse.
Nowlet’slookatitfromtheman’spointofview.Fromhispointofview,theprobabilitiesaredifferent.Fromhispointofview,theprobabilitythathehasanorangeis100%or0%.That’sbecauseheknowswhathehas.Forhimthereisnouncertainty.Ifhehasanorange,theprobabilityis100%.Ifhedoesn’thaveanorange,theprobabilityis0%.?
Heeitherhasitorhedoesn’t.
Fromourpointofview,theprobabilitythathehasanorangeis50%.Fromhispointofview,theprobabilitythathehasanorangeis100%or0%.Sotheprobabilitydependsonyourpointofview.
Peopleseethingsfromdifferentpointsofview.Thisoftenleadstoargumentsbetweenpeople.Herearesomeexamples.Fromthisman’spointofview,heisrelaxing.Heneedstorelaxbecausehehasbeenworkingtoohard.Hehasn’tbeengettingenoughsleep.
Hiswifeseesthingsdifferently.Sheisn’tawareofhowhardhehasbeenworking.Fromherpointofview,heisdoingnothing.However,sheknowswhatneedstobedonearoundthehouse.Itisn’tfairthatshehastoworkwhilehedoesnothing.
Whenpeopleseethingsfromdifferentpointsofview,theyoftencometodifferentconclusions.Thesedifferencescancauserealcommunicationproblems.
Level4Unit2Part2Vocabulary
Disasters
Earthquakesarecausedbyforcesdeepwithintheearth.Whentheearthshakes,buildingscancollapseandpeoplecanbeburiedinside.
Anexplosionisarapid,violentreleaseofenergy.Explosionscanbecausedbychemicalreaction,suchasinsideanengine.Asparkcanigniteamixtureofgases,andreleaseenergyforgoodordestructivepurposes.
Accidentsareoftencausedbypeopledoingfoolishthingsorbynotbeingcareful.Onemajorcauseofaccidentsisdrivingtoofast.Accidentswithfirecanbeveryseriousandcanresultinverypainfulinjuries.
Epidemicsaretherapidspreadofadisease,suchasthefluorEbola.Throughouthistoryepidemicshavekilledmillionsofpeople.
Stormsarecausedbychangesintheatmosphereresultinginhighwindsandheavyrain.Thunderstormsarecausedbyelectricchargesintheatmospherethatproducelightning,whichcancauseforestfires.Somestorms
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