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1、外语下载中心http://down.tingroom.comLesson1Wecanreadofthingsthathappened5,000yearsagointheNearEast,wherepeoplefirstlearnedtowrite.Buttherearesomepartsoftheworldwhereevennowpeoplecannotwrite.Theonlywaythattheycanpreservetheirhistoryistorecountitassagas--legendshandeddownfromonegener
2、ationofstory-tellerstoanother.Theselegendsareusefulbecausetheycantellussomethingaboutmigrationsofpeoplewholivedlongago,butnonecouldwritedownwhattheydid.AnthropologistswonderedwheretheremoteancestorsofthePolynesianpeoplesnowlivinginthePacificIslandscamefrom.Thesagasofthesepeop
3、leexplainthatsomeofthemcamefromIndonesiaabout2,000yearsago.Butthefirstpeoplewhowerelikeourselveslivedsolongagothateventheirsagas,iftheyhadany,areforgotten.Soarchaeologistshaveneitherhistorynorlegendstohelpthemtofindoutwherethefirst'modernmen'camefrom.外语下载中心http://down.tingroo
4、m.com外语下载中心http://down.tingroom.comFortunately,however,ancientmenmadetoolsofstone,especiallyflint,becausethisiseasiertoshapethanotherkinds.Theymayalsohaveusedwoodandskins,butthesehaverottedaway.Stonedoesnotdecay,andsothetoolsoflongagohaveremainedwheneventhebonesofthemenwhomad
5、ethemhavedisappearedwithouttrace. Lesson2Why,youmaywonder,shouldspidersbeourfriends?Becausetheydestroysomanyinsects,andinsectsincludesomeofthegreatestenemiesofthehumanrace.Insectswouldmakeitimpossibleforustoliveintheworld;theywoulddevourallourcropsandkillourflocksandherds,ifi
6、twerenotfortheprotectionwegetfrominsect-eatinganimals.Weowealottothebirdsandbeastswhoeatinsectsbutallofthemputtogetherkillonlyafractionofthenumberdestroyedbyspiders.Moreover,unlikesomeof外语下载中心http://down.tingroom.com外语下载中心http://down.tingroom.comtheotherinsecteaters,spidersne
7、verdotheleastharmtousorourbelongings.Spidersarenotinsects,asmanypeoplethink,norevennearlyrelatedtothem.Onecantellthedifferencealmostataglanceforaspideralwayshaseightlegsandaninsectnevermorethansix.Howmanyspidersareengagedinthisworkonourbehalf?Oneauthorityonspidersmadeacensuso
8、fthespidersinagrassfieldinthesouthofEngland,andheestimatedthattherew
