unit3listening(WB)课件
日期：2010-04-15 04:42
withflamesusuallyaboutasthickastheyarehighForestfiresnormallytravelatonetothreekm/h，thedangerperiodissummerandautumnForNewSouthWalesandsouthernQueensland，thepeakriskusuallyoccursinspringandearlysummerNorthernAustraliaexperiencesmostofitsfiresinwinterandspringBushfiresinAustraliaspreadasathinfrontofflame，dryandpronetodroughtInthesoutheast，andwillpassaspotin30-60secondsSevereforestfirestravelatupto12km/h，withflames100-l50metreshighandthickGrassfiresgenerallytravelaboutthreetotenkm/h，1Whatdoyouknowaboutbushfires?2Howdotheystart?3Wheredotheyhappen?4Doyouthinkwhichcountryisthretedbybushfiresmost?TheAustralianclimateisgenerallyhot，haveflames10-20metreshighandthick，occasionalstrongwindswithsummertimecanleadtoextremefiredangerManyofAustralia‘snativeplantsburneasilyTheeucalypts’(桉树)highoilmakesthemparticularlyfireprone(倾向)Thevastareasofdrygrasscommoninmid-to-latesummeralsoburnreadilyVariedfireseasonsreflectdifferentweatherpatternsFormostofsouthernAustralia，bu，
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