高二英语unit10

用心爱心专心高二英语Unit10Frighteningnature知识精讲人教版一.本周教学内容：Unit10Frighteningnature二.教学目标：1.Mastersomephrasesandsentencepatterns2.Talkaboutnaturaldisasters:volcanoesandtyphoons3.Writeacreativewriting三.教学重点与难点：LearnaboutEllipsis四.具体内容：BackgroundinformationVolcanoesTherearethousandsofvolcanoesallovertheworld.Whatmakesvolcanoes?Whathappens?Theinsideoftheearthisveryhot.Becauseitisvery,veryhot,therockhasmeltedlikeice.Ithasbecomeliquid,likewater.Itisalwaysboiling,likewaterinakettle.Ifyouhaveseenakettleboiling,youknowthatthesteamandboilingwatertrytogetout.Theveryhotmeltedrockinsidetheearthalsotriestogetout.Usuallyitcannotbecausetheoutsideoftheearthistoothickandstrong.Butinsomeplacestheoutsideoftheearthisthinandweak.Sometimesacrackappears.Thehotmeltedrock,whichwecall“lava”,pushesupthroughthecrackandburststhrough.Steamandgasshootupintotheairandthehotmeltedlavapoursout.Bigpiecesofrockmaybethrownhighintotheair.Afterawhilethevolcanobecomesquietagain.Themeltedlavabecomeshard.Laterthesamethinghappensagainandagain.Eachtimemorehotlavapoursoutontopofthecoldlavaandthenbecomeshard.Inthiswayakindofmountainisbuiltup,withaholedownthemiddle.Perhapsthevolcanowillthenbequietandnomorelavawillburstout.Perhapsitwillstartagainhundredsofyearslater.Althoughtherearethousandsofvolcanoesintheworld,mostofthemaredead.Onlyabout500sometimesstarttothrowoutlavaagain.AfamousvolcanowhichisnowdeadisMountFujiyamainJapan.Itiscoveredwithsnowinwinter.VesuviusisthenameofaveryfamousvolcanoinItaly.Itfirstcametolifemany,manyyearsago.Itwasquietforhundredsofyears.Thenintheyear79itsuddenlyburst.Agreatcloudofsmokeshotupintotheskywithgreatburningrocks,whichfellallaround.Hotlavapoureddownitssides.About3000peoplewerekilled.Thishashappenedagainmanytimessincethatyear.Sometimesnodamagewascaused,oronlylittledamage.Buttherewasseriousdamageintheyears472,1631,1794,1861,1872and1906.Youcanseethatavolcanocanstayaliveformanyyears.In1906partofthetopofthemountainfelloff.Therewasalsoseriousdamagein1914buttherehasnotbeenanysincelastyear.Fireandsmokecomingfromthetopofthemountainhavealwaysmadepeoplecuriousaboutthesourceofthatfireandwhattheinterioroftheearthmightlooklike.Thepower,heatand用心爱心专心brightredandorangecolorsofmeltenrockareasfascinatingasever.Manyaccidentshavehappenedtopeoplewhoaredrawntooclosetoobservethismaginificentspectacle.Peoplehavealwaysknownvolcanoestobedangerous.Nonetheless,wefindhumancommunitiesandvillagesbuiltatthefootofmanyvolcanoeseverywherearoundtheworld.Thisisbecausetheeartharoundvolcanoesisveryfertile,sofarmerswerealwaysattractedtoplanttheircropsnearthesemountains.Also,thefactthatsomevolcanoeshavelongperiodsoftimewithoutbeingactive,hasoftengivenpeopleasenseofsecurity.Somevolcanoesthathadbeeninactiveformanygenerationsandwerethoughttobedead,suddenlysprangbacktolifeandkilledthousandsofpeople.TornadoThephenomenonusuallyoccursonahot,stickydaywithsouthwindsandanominoussky.Fromthebaseofathunderhead,afunnel-shapedcloudextendsaviolentlytwistingspouttowardtheearth.Asitsucksinmatterinitspath,thetwistermayturnblack,brown,oroccasionallyevenwhite.Themovingcloudshowsanalmostcontinuousdisplayofsheetlightening.Itlurchesalonginameanderingpath,usuallynortheastward,at25to40milesperhour.Sometimesitpicksupitsfingerfromtheearthforashortdistanceandthenplantsitdownagain.Thefunnelisveryslender,itswakeofviolenceaveragesabout400yardswide.Asthetornadoapproaches,itisheraldedbyaroarasofhundredsofjetplanesorthousandsofrailroadcars.Itspathisapathoftotaldestruction.Buildingsliterallyexplodedastheyaresuckedinbythetornado’slow-pressurevortexandbyitspowerfulwhirlingwinds.Thetornado’slifetimeisasbriefasitisviolent.Withinafewtensofmiles,itspendsitsforceandsuddenlyappears.EarthquakesEarthquakeisasudden,violentshakingoftheearth’ssurface.It’sakindofcrustalmovementformofexpression.Earthquakeisregardedasoneofthemostdamagingforcesknowntoman:sincerecordsbegantobewrittendown,ithasbeenestimatedthatearthquake-relatedfatalitieshavebeennumberedinthemillions,andthatearthquake-relateddestructionhasbeenbeyondcount.Thegreatmajorityofallearthquakesoccurintwospecificgeographicareas.OnesuchareasurroundsthePacificOceananditscontiguouslandmasses.TheotherextendsfromtheEastIndiatotheAtlasMountains,includingtheHimalayas,Iran,Turkey,andtheAlpineregions.Itisinthesetwogreatbeltsorzonesthatninetypercentofallearthquakestakeplace.Astoourcountry,alargenumberofearthquakeshappenedinNorthChinaandNorthwestChina.ThepowerfulearthquakeofTangshanhappenedinthecityofTangshan,HebeiProvinceonJuly28th,1976,whichcausedmorethan240,000deathsandthewholecitywasdestroyed.TyphoonsTyphoonsarefrequentalongthesoutheastcoastofChinaandonthesouthChineseislandTaiwanandHainan.Theycancausealotofdamageandevenlossoflife.Still,topeoplewhoareusedtothem,theyaremostlyanuisanceandseldomaseriousthreat.Ifyouarelivinginanareawheretyphoonsoccur,peopleusuallyknowhowtoprepareforthem.TyphoonisaChineseloanwordthatisnowusedIEnglish.Similarkindsofwindsarecalledhuricanesorcyclones.用心爱心专心LanguagePoints1.threatn.（1）威胁；恐吓（2）凶兆carryoutathreattodosth.扬言要做某事beathreattosb’sliferelievethethr