2019外研版高一英语必修一 unit5课文

Understandingideas必修一unit5TheMonarch'sJourneyManyanimalsmovefromoneplacetoanotheratcertaintimesoftheyear.Thisannualmovementiscalledmigration.Theymigratetofindfood,seekapartner,orinsearchofwarmerweather.OneofthemostwonderfulmigrationsinnatureisthatoftheNorthAmericanmonarchbutterfly.Everyautumnmillionsofthesebeautifulinsectswithafineblackandorangewingsbeginalonganddifficultjourney.Somehowtheymanagetotravelaround4,000kilometerssouthandfindtheirwaytoCaliforniaorMexico.However,untilrecentlynooneknewhowtheydidthis.AteamofscientistsledbyProfessorEliShlizermanattheUniversityofWashingtonhasnowfoundtheanswer.Theyhavefoundoutthatthemonarchisabletotellthetimeofday.Itusesitseyestomeasurethepositionofthesun.ThesetwopiecesofIinformation-thetimeofdayandthepointwherethesunisinthesky-allowedthebutterflytodeterminethewaytogo.Eventually,itmanagestoreachtheplaceswhereitwillspendthewinter.Thesolutiontothemysteryofthemonarch'samazingabilitycomesatatimewhenitisinserioustrouble.Itspopulationhascrashedbyasmuchas90percentinthelastfewyears.Sadly,humanactivityisthemainreasonwhythenumberofmonarchbutterfliesisfalling.Inmanyoftheplaceswherethebutterflycanbefound,peoplearedestroyingthenaturalenvironment.Theycutdowntreesandusechemicalsthatkilledplantsthatmonarchcaterpillarseat.Theresearchonthemonarch'sbehaviorhashoweverledtoagreaterawarenessofthiscreature.Peoplehavebeenworkingtogethertorecorditsmigrationandmakesurethatthereareenoughplansforittofeedon.Ifthisworks,theremaycomeatimewhenthenumberofmonachbutterfliesincreasesonceagain.Themoreweknowaboutthislovelycreature,thegreaterthechanceitwillsurviveandkeepitsplaceinthenaturalworldforalongtimetocome.DevelopingideasAnEncounterwithNatureAsanaturephotographer,Ihavetobravetheelements.ButdespitethewindandtherainIstillenjoyworkingoutsideinthewild.Oneofthebestthingsaboutthisjobisthatyoucanobserveanimalsintheirnaturalenvironment.MyfavoriteplacetotakephotosisYellowstoneNationalPark.Astheworld'sfirstnationalpark,Yellowstoneisfamousforthevarietyofitswildlife,butitisprobablybestknownforitsbears.Thesehuge,stronganimalscanlivefor30years.Despiteaweightofupto300kilograms,theycanrunataspeedofaround64kilometersperhourandarealsoexcellentswimmers.LastspringinYellowstone,Ifollowedapaththattookmethroughadarkforest.WhenIfinallysteppedoutofthetrees,theviewwasbreathtaking.Aneagleflewoverthesnowcappedmountainswhichwerereflectedinthestilllakebelow.Well,Iwasconcentratingonphotographingthisamazingscene,IsuddenlyhadafeelingthatIwasbeingwatched.Slowly,andwiththecamerastillheldtomyeye,Iturned...andfroze.Onlymetersawayfrommewasabear.Withwaterfallingoffitsthick,brownhair,thebearstaredbackatme.TimestoodstillasthebearandIbothwaitedtoseewhowouldmovefirst.Mylegsstartedshaking.Somehow,Iforcedmyfingertopressthebutton.Asecondlater,thebearturnedandranbackintotheforest.WhenIrecoveredfromtheshock,Ilookedatmycamera.Mymostfrighteningbutmagicalexperiencewasnowcapturedforeverinasingleimage.FromtimetotimeIlookedatthephotoasaremindertoshowrespecttoallanimals.Itisafterallwewhoarethevisitorstotheirworld.WritingananimalfactoffileThered-crownedcraneisoneofthelargestcranesintheworld,standingatabout150cmtall.Itsfeathersareaswhiteassnow,exceptforsomeblackonesonitsface,neckandwings.It'suniquefeather,fromwhichitgetsitsnameisthebrightredskinonthetopofitshead.Thered-crownedcraneisfoundinChina,Russia,Mongolia,JapanandtheKoreanPeninsula.InChina,itspendsthewarmermonthsintheriversandwetlandsinthenorth-east.Whentheweathergetscold,itmigratestoeast-centralChina.It'sfoodincludesfish,snailsandwaterplants.Thered-crownedcraneisasymboloflonglifeandgoodluckinChineseculture.