懂你英語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.)

FollowersofJudaismarecalledJews.TheseJewsaremeetinginsideasynagogue,whichisaplaceofworshipandstudy.Judaismwasfoundedover35hundredyearsagointhemiddleeast.JudaismisbasedontheteachingsofMoses,whotheybelieveisthemostimportantprophet.

BuddhismbeganinIndiaandisbasedontheteachingsoftheBuddha.Thereligionisabout25hundredyearsold.SomeBuddhistspracticeaformofmeditationinwhichtheyemptytheirmindsofanythought.

Hinduismistheworld’sthirdmostpopularreligionandisthemainreligionofIndia.Hinduismhasnofounderandisamixtureofmanybeliefs.SomeHindusbelieveinthecycleofbirth,life,deathandrebirth.

Level4Unit2Part2Dialogue

MissingAircraft

Doyouhaveanymoreinformationaboutthelocationofthemissingaircraft?

No,wedon’t.Theonlyinformationwehaveisthatitdisappeared.

Whataboutthelastcommunicationwiththeaircraft?

Thelastcommunicationwasabout15minutesbeforeitdisappeared.

Wasthereanythingunusualinthecommunication?

No,therewasn'tanythingunusual.

Nothingpointedtoanykindofproblem.

Anyway,weareconfidentthatwewillfindit.

It’salargeaircraftsoitshouldn’tbedifficulttofind.

Howmanycountriesarehelpingwiththesearch?

Rightnow,wehavesearchteamsfrom3countriesstartingthesearch.

It’sabigareatosearch,socanyougiveusanestimateabouthowlongitwilltake?

Yes,it’sabigarea,soitmighttakealongtime.

Butwewon’tgiveup.

Wewillsearchuntilwefindit.

Havetheyfoundthewreckageyet?

Whatareyoutalkingabout?

Youknow,theairplanethatdisappearedlastyear.

Oh,yes,nowIknowwhatyouarereferringto.

Yes,theyfoundsomepieceofit.

Whatabouttheblackboxes?

No,theystillhaven’tfoundtheblackboxes.

It’shardtobelievetheystilldon’tknowwhathappened.

Perhapsthey’llneverknow,especiallyiftheydon’tfindtheblackboxes.

Whateverhappenedtoit,thereisnogoodreasonwhyamodernairlineisallowedtodisappear.

Iagreewithyou.

懂你英語L4-Unit23

Level4Unit2Part3Listening

Alcatraz

AlcatrazisasmallislandinSanFranciscoBay,1.5milesfromSanFrancisco.FromAlcatraz,youcanseethefamousGoldenGateBridge.Alcatrazisalsofamousandisnowamajortouristattraction.Touristscanreachtheislandbyboatfromthecity.

Alcatrazhasoftenappearedinmovies,including"EscapefromAlcatraz"whichwasmadein1979.Onereasonit’sfamousisbecauseitusedtobeaprison,averyspecialprison.Itwasdesignedforprisonerswhowerecausingtroubleinotherprisons,suchastryingtoescape.Itwasamaximumsecurityprison,soescapewasalmostimpossible.Thewatersarounditarecold,andonlyverystrongswimmerscanswimfromtheislandtoSanFrancisco.

Thefirstgroupofprisonersarrivedin1934.Therewere137prisoners,includingbankrobbersandmurderers.TheycamebytrainfromanotherprisoninthestateofKansas.Duringthattrip,therewasheavysecurity.Theprisonerswereunderguardandhandcuffed.Nobodywantedthemtoescape.

Theprisonwasdesignedtoholdupto336prisoners.However,theaveragepopulationwasonlyabout270.Althoughtherewereseveralnotoriousinmates,suchasAlCapone,mostoftheinmateswerenotwell-known.Manyhadtriedtoescapefromotherprisonsorwereconsideredviolent.Ifamandidnotbehaveatanotherprison,hecouldbesenttoAlcatraz.AtAlcatraztherewasjustoneinmateineachprisoncell.

PrisonlifeatAlcatrazwashighlystructuredandboring.Itwasdesignedtoteachprisonerstofollowrules.Theyhadfourrights:food,clothing,shelter,andmedicalcare.Everythingelsewasaprivilegethathadtobeearned.Privilegesincludedworking,visitsfromfamilymembers,andaccesstotheprisonlibrary.Therewerealsoactivitiessuchaspaintingandmusic.Onceaprisonershowedthathecouldfollowtherules,hecouldbetransferredbacktoanotherprisontofinishhissentence.

Alcatrazwasusedasaprisonfor29years.Duringthattime,noprisonerescapedsuccessfully.Therewere14escapeattempts,involving36prisoners.Twenty-threewerecaughtalive,andsixwereshotandkilled.Twomentriedtoescapetwice.Twodrownedandfivewerelistedasmissingandpresumeddrowned.ThemostviolentescapeattemptoccurredonMay2,1946whensixprisonerstriedtoescape.Thateventiscalledthe"BattleofAlcatraz."

Whileitwasinuse,AlcatrazheldsomeofthemostnotoriouscriminalsinAmericanhistory,suchasAlCapone.AlCaponewasacrimebosswhobuilthiscareerinChicago.Theprisonwasfinallyclosedin1963.Itwasclosedbecauseitwastooexpensivetooperate.

Level4Unit2Part2Vocabulary

Graphs&charts

Abargraphusesrectangularbarsofdifferentlengthstoshowandcomparedata.Thelengthsofthebarsareproportionaltothevaluestheyrepresent.Thebarscanbevertical,upanddown,orhorizontal.

Acirclegraph,oftencalledapiegraph,isshapedlikeacircle.Itisdividedintosegmentsthatlooklikepiecesofapie.Percentagesareusedtocomparethesegments,whichareorderedfrombiggesttosmallest.

Linegraphsareusedtoshowtherelationshipbetweentwovariables,suchastimeanddistance.Thesevariablesareplottedon2axes,theXaxisandtheYaxis.TheXaxisoftenshowstime,whiletheYaxisshowshowquantities,suchasdistance,temperature,orprofitschangewithtime.

Aflowchartisatypeofgraphthatshowshowaprocessoraprojectflowsfromstarttofinish.Aflowchartconsistsofstartpoints,inputs,outputsanddecisionpoints.

Anorganizationalchartororgchartshowthestructureofacompany.Itshowshowpeopleanddepartmentswithinacompanyareconnected.Itdefinestherolesandresponsibilitiesofpeopleanddepartmentswithinacompany.

LegalTerms

Lawsarerulesthatpeoplearesupposedtofollow.Asystemoflawsgovernsthebehaviorofpeoplewithinacountry.(Anactionthatisagainstthelawisanillegalaction.)(Anactionthatfollowsthelawisalegalaction.)

Criminalsarepeoplewhobreakthelaw.Peoplewhocommitacrimearecalledcriminals.Somecriminalsareverydangerousandneededbeputinjail.(Someonewhocommitsacrimemaybesenttoprison.)

Ajailorprisonisaplacewherecriminalsarelockedbehindbars,sometimesformanyyears.Prisonsaredesignedtokeepcriminalsawayfromotherpeople.

Acourthous