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1、外语下载中心http://down.tingroom.comLesson1Wecanreadofthingsthathappened5,000yearsagointheNearEast,wherepeoplefirstlearnedtowrite.Buttherearesomepartsoftheworldwhereevennowpeoplecannotwrite.Theonlywaythattheycanpreservetheirhistoryistorecountitassagas--legendsh
2、andeddownfromonegenerationofstory-tellerstoanother.Theselegendsareusefulbecausetheycantellussomethingaboutmigrationsofpeoplewholivedlongago,butnonecouldwritedownwhattheydid.AnthropologistswonderedwheretheremoteancestorsofthePolynesianpeoplesnowlivinginthe
3、PacificIslandscamefrom.ThesagasofthesepeopleexplainthatsomeofthemcamefromIndonesiaabout2,000yearsago.Butthefirstpeoplewhowerelikeourselveslivedsolongagothateventheirsagas,iftheyhadany,areforgotten.Soarchaeologistshaveneitherhistorynorlegendstohelpthemtofi
4、ndoutwherethefirst'modernmen'camefrom.外语下载中心http://down.tingroom.com外语下载中心http://down.tingroom.comFortunately,however,ancientmenmadetoolsofstone,especiallyflint,becausethisiseasiertoshapethanotherkinds.Theymayalsohaveusedwoodandskins,butthesehaverottedawa
5、y.Stonedoesnotdecay,andsothetoolsoflongagohaveremainedwheneventhebonesofthemenwhomadethemhavedisappearedwithouttrace. Lesson2Why,youmaywonder,shouldspidersbeourfriends?Becausetheydestroysomanyinsects,andinsectsincludesomeofthegreatestenemiesofthehumanrace
6、.Insectswouldmakeitimpossibleforustoliveintheworld;theywoulddevourallourcropsandkillourflocksandherds,ifitwerenotfortheprotectionwegetfrominsect-eatinganimals.Weowealottothebirdsandbeastswhoeatinsectsbutallofthemputtogetherkillonlyafractionofthenumberdest
7、royedbyspiders.Moreover,unlikesomeof外语下载中心http://down.tingroom.com外语下载中心http://down.tingroom.comtheotherinsecteaters,spidersneverdotheleastharmtousorourbelongings.Spidersarenotinsects,asmanypeoplethink,norevennearlyrelatedtothem.Onecantellthedifferencealm
8、ostataglanceforaspideralwayshaseightlegsandaninsectnevermorethansix.Howmanyspidersareengagedinthisworkonourbehalf?OneauthorityonspidersmadeacensusofthespidersinagrassfieldinthesouthofEngland,andheestimatedthattherew
