Therehavebeenmanygreatinventionswhichhavechangedthewaywelive.Thefirstgreatinventionwasonethatisstillveryimportanttoday---thewheel.Thismadeiteasiertocarryheavythingstotravellongdistances.Forhundredsofyearsafterthattherewerefewinventionsthathavemadeasmucheffectasthewheel.Therewaslittleunknownlandleftintheworld.Peopledidn'thavetoexplore(开发)muchanymore.Theybegantoworkinsteadtomakelifebetter.

Inthesecondhalfofthe19thcenturymanygreatinventionsweremade.Amongthemwerethecameratheelectriclightandtheradio.Theseallbecameabigpartofourlifetoday.Thefirstpartofthe20thcenturysawmoregreatinventions.Thehelicopterin1909.Soundmoviesin1926.Thecomputerin1928andjetplanesin1930.Thiswasalsoatimewhenanewmaterialwasmade.Nyloncameoutin1935.Itchangedthekindofclothespeoplewear.Themiddlepartofthe20thbroughtnewwaystohelppeoplegetoverdiseases.Theyworkedverywell.Theymadepeoplehealthierandletthemlivelonglives.Bythe1960smostpeoplecouldexpecttolivetobeatleast60.Bythistimemostpeoplehadaverygoodlife.Ofcoursenewinventionscontinuedtobemade.Butmannowhadawishtoexploreagain.Theworldisknowntomanbutthestarsarenotyet.Manbeganlookingforwaystogointospace.Russiamadethefirststep.ThentheUnitedStatestookastep.SincethenothercountriesincludingChinaandJapanhavemadetheirstepsintospace.

68.Thefirstgreatinventioneverknownwas______.

A.thecamera B.thewheel C.theelectriclight D.theradio

69.Whichofthefollowingwasturnedoutnearlyatthesametimewiththejetplane?

A.Theradio. B.Thecamera.

C.Nylon. D.Thehelicopter.

70.Thispassagetalksmainlyabout______.

A.howinventionsaffect(影响)people'slife B.whenelectriclightwasinvented

C.whichcountrymadethefirststepintospace D.whycarswereveryimportant

71.Wecansafelycometotheconclusionthatpeople'slifewillbemadeevenbetterthrough______.

A.newdiscoveries?