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1、新概念英语第四册Lesson1Wecanreadofthingsthathappened5,000yearsagointheNearEast,wherepeoplefirstlearnedtowrite.Buttherearesomepartsoftheworldwhereevennowpeoplecannotwrite.Theonlywaythattheycanpreservetheirhistoryistorecountitassagas--legendshandeddownfromonegenerationofstory-tellerstoanother.
2、Theselegendsareusefulbecausetheycantellussomethingaboutmigrationsofpeoplewholivedlongago,butnonecouldwritedownwhattheydid.AnthropologistswonderedwheretheremoteancestorsofthePolynesianpeoplesnowlivinginthePacificIslandscamefrom.ThesagasofthesepeopleexplainthatsomeofthemcamefromIndones
3、iaabout2,000yearsago.Butthefirstpeoplewhowerelikeourselveslivedsolongagothateventheirsagas,iftheyhadany,areforgotten.Soarchaeologistshaveneitherhistorynorlegendstohelpthemtofindoutwherethefirst'modernmen'camefrom.Fortunately,however,ancientmenmadetoolsofstone,especiallyflint,becauset
4、hisiseasiertoshapethanotherkinds.Theymayalsohaveusedwoodandskins,butthesehaverottedaway.Stonedoesnotdecay,andsothetoolsoflongagohaveremainedwheneventhebonesofthemenwhomadethemhavedisappearedwithouttrace. Lesson2Why,youmaywonder,shouldspidersbeourfriends?Becausetheydestroysomanyinsect
5、s,andinsectsincludesomeofthegreatestenemiesofthehumanrace.Insectswouldmakeitimpossibleforustoliveintheworld;theywoulddevourallourcropsandkillourflocksandherds,ifitwerenotfortheprotectionwegetfrominsect-eatinganimals.Weowealottothebirdsandbeastswhoeatinsectsbutallofthemputtogetherkill
6、onlyafractionofthenumberdestroyedbyspiders.Moreover,unlikesomeoftheotherinsecteaters,spidersneverdotheleastharmtousorourbelongings.Spidersarenotinsects,asmanypeoplethink,norevennearlyrelatedtothem.Onecantellthedifferencealmostataglanceforaspideralwayshaseightlegsandaninsectnevermoret
7、hansix.Howmanyspidersareengagedinthisworkonourbehalf?OneauthorityonspidersmadeacensusofthespidersinagrassfieldinthesouthofEngland,andheestimatedthatthereweremorethan2,250,000inoneacre,thatissomethinglike6,000,000spidersofdifferentkindsonafootballpitch.Spidersarebusyforatleasthalfthey
8、earinkilling
