高一英语完形填空一篇答案已给,每题求原因.请解释清楚,本人初三学生.

Thecentralproblemofeconomicsistosatisfythepeople'sandnation'swants.

Theproblemwearefacedwithisthatourresources,hereidentifiedasmoney,are__1__.Theonlywaywecanresolveourproblemistomakechoices.Afterlookingatourresources,wemustexamineourlistof__2__andidentifythethingsweneedimmediately,thosewecanpostpone,and__3__wecannotafford.Asindividuals,wefacethecentralprobleminvolvedineconomics-decidingjusthowtoallocateourlimitedourlimitedresourcestoprovide__4__withthegreatestsatisfactionofourwants.

Nationsfacethesameproblem.Asacountry'spopulation___5__,theneedformoregoodsandservicesgrowscorrespondingly.Resourcesnecessarytoproductionmayincrease,butthere__6__areenoughresourcestosatisfythetotaldesiresofanation.Whetherthebudgetmeetingistakingplaceinthefamilylivingroom,intheconferenceroomofthecorporation__7__ofdirectors,orinthechamberoftheHouseofRepresentativesinWashington,thebasicproblemstillexists.Weneedtofind__8__ofallocatinglimitedresourcesinordertosatisfyunlimitedwants.

Ashorttimeagoeconomistsdividedgoodsintotwocategories,freeandeconomic.Theformer,likeairandwater,werein__9__abundancethateconomistshadnoconcernforthem.Afterall,economicsisthe__10__ofscarcityandwhattodoaboutit.Todaymanyofthese"freegoods"are__11__veryexpensivetouse.Pollutionhasmadecleanairandwaterexpensiveforproducers'extracosts,and__12__taxpayerswhopayforthegovernment'sinvolvementincleaningtheenvironment.

Inthe1990s,almostallgoodsare__13__.Onlybyeffortandmoney__14__obtainedintheformpeoplewish.

Meetingneedsofpeopleandthedemandsfromresourceavailable__15__thebasicactivityofproduction.Intryingtomeetunlimitedwantsfromlimitedeconomicgoods,productionleadstonewproblemsineconomics.

EXERCISE:

1.A)limitedB)unlimitedC)scarcityD)abundant

2.A)wantB)problemC)wantsD)resources

3.A)thoseB)someC)othersD)many

4.A)themB)themselvesC)ourselvesD)ours

5.A)expandB)extendsC)growsD)increase

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