BenandhisclassmatesarewatchingaDVDabouttheenvironment.Thisistheintroductiontothevideo,wherethenarratorexplainswhattheDVDisabout.Alongtimeago,mosttownsandvillageswereverysmall.Thenumberofpeoplewhol

　　BenandhisclassmatesarewatchingaDVDabouttheenvironment.Thisistheintroductiontothevideo,wherethenarratorexplainswhattheDVDisabout.

　　Alongtimeago,mosttownsandvillageswereverysmall.Thenumberofpeoplewholivedineverycountrywasmuchsmallerthanitistodaytoo.Therewasnoheavyindustry,onlyagricultureandartsandcraftsandnoneofthesethingsdamagedourenvironment.Peopledidnotusechemicals.Therewerenomotorvehicles.Therewerenofactories.Therewas,therefore,verylittlepollution.

　　Sadly,ourenvironmentismuchdirtierthanitwasinthepast.Thisisaproblembecausethebestwayforustobehealthyistoliveinacleanenvironment.

　　Theairandwateraremuchdirtierthantheyusedtobe.Theairisfullofpollutantsofallkinds—smokefromcarsandfactoriesandsuchthingsasinsectsprays.Thewaterispollutedwithchemicalsfromfactoriesandfuelfromships.Thismeansthatwearegraduallydestroyingoneofourmajorfoodsources—theoceansoftheworld.

　　IntheDVDwewilltrytofindwaystomakeourenvironmentcleanerandwaystostopfuturepollution.Wehopeyouwilllearnhowyoucanhelpmaketheworldacleanerandhealthierplace.

　　Choosethebestanswer:

　　Therewaslesspollutioninthepastbecause________.

　　A

　　thetownsweresmaller

　　B

　　peopledidn'thaveDVDs

　　C

　　peopledidn'thaveanythingthatdamagedtheenvironment

　　D

　　peopleknowhowtomaketheenvironmentcleaner

　　Peoplehad________beforeheavyindustry.

　　A

　　agricultureandmotorvehicles

　　B

　　factories,artsandcrafts

　　C

　　agriculture,factoriesandchemicals

　　D

　　agricultureandartsandcrafts

　　Theairisdirtiernowthanitwasinthepastbecause________.

　　A

　　it'spollutedwithchemicals

　　B

　　it'sfullofsmokeandinsectsprays

　　C

　　it'spollutedwithfuel

　　D

　　therearen'tdirtywater

　　Oceansareimportantbecause________.

　　A

　　theyareamajorsourceofchemicals

　　B

　　theyareamajorsourceoffood

　　C

　　theya