2016年职称英语卫生类概括大意模拟试题及答案

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1、2016年职称英语卫生类概括大意模拟试题及答案　　VoltsfromtheSky　　Lightninghascausedaweandwondersinceoldtimes.AlthoughBenjaminFranklindemonstratedlightningasenormouselectricaldischargemorethan200yearsago，manypuzzlesstillsurroundthispowerfulphenomenon.　　Lightningisgeneratedwhenelectricalcharge

2、sseparateinrainclouds，thoughprocessesarestillnotfullyunderstood.Typically，positivechargesbuildatthecloudtop，whilethebottombecomesnegativelycharged.Inmostinstancesofcloud-to-groundlightning，thenegativelychargedlowerportionofthecloudrepelsnegativelychargedparticlesontheg

3、roundssurfaces，makingitbecomepositivelycharged.Thepositivechargeonthegroundgathersatelevatedpoints.　　Aflowofelectronsbeginsbetweenthecloudandearth.Whenthevoltagechargebecomeslargeenough，itbreaksthroughtheinsulatingbarrierofair，andelectronszigzagearthward.Weseethedischa

4、rgeaslightning.　　Lightningcanoccurwithinacloud，betweenclouds，orbetweencloudsandtheground.Thefirstvariety，intra-cloudlightning，isthemostfrequentbutisoftenhiddenfromourview.Cloud-to-groundlightning，makingupabout20percentoflightningdischarges，iswhatweusuallysee.Lightningc

5、omesinseveralforms，includingsheet，ribbon，andball.Intra-cloudlightningcanilluminateacloudsoitlookslikeawhitesheet，henceitsname.Whencloud-to-groundlightningoccursduringstrongwinds，theycanshiftthelightningchannelsideways，soitlookslikearibbon.Theaveragelightningstrikeismor

6、ethan3mileslongandcantravelatatenthofthespeedoflight.Balllightning，therarestandmostmysteriousform，derivesitsnamefromthesmallluminousballthatappearsneartheimpactpoint，moveshorizontally，andlastsforseveralseconds.　　Thunderisgeneratedbythetremendousheatreleasedinalightning

7、discharge.Temperaturesnearthedischargecanreachashighas50，000°Fwithinthousandthsofasecond.Thissuddenheatingactsasanexplosion，generatingshockwaveswehearasthunder.　　About2，000thunderstormsareoccurringintheworldatanytime，generatingabout100lightingstrikeseverysecond，or8mill

8、iondaily.WithintheUnitedStates，lightningstrikesareestimatedat20millionayear，orabout22，000perday.Youhavea1-in-600，000c