Thebackgardenofourhousecontainsalawn，（）verypleasanttositoninsummer.

Scatteredthroughtheseasoftheworldarebillionsoftonsofsmallplantsandanimalscalledplankton.Mostoftheseplantsandanimalsaretoosmallforthehumaneyetosee.Theydriftaboutlazilywiththecurrents,providingabasicfoodformanylargeranimals.Planktonhasbeendescribedastheequivalentofthegrassesthatgrowonthedrylandcontinents,andthecomparisonisanappropriateone.Inpotentialfoodvaluehowever,planktonfaroutweighsthatofthelandgrasses.Onescientisthasestimatedthatwhilegrassesoftheworldproduceabout49billiontonsofvaluablecarbohydrateseachyear.Thesea’splanktongeneratesmorethantwiceasmuch.

Despiteitsenormousfoodpotential,littleeffortwasmadeuntilrecentlytofarmplanktonaswefarmgrassesonland.Nowmarinescientistshaveatlastbeguntostudythispossibility,especiallyasthesea’sresourcesloomevenmoreimportantasameansoffeedinganexpandingworldpopulation.

Nooneyethasseriouslysuggestedthat“planktonburgers”maysoonbecomepopulararoundtheworld.Asapossiblefarmedsupplementaryfoodsource,however,planktonisgainingconsiderableinterestamongmarinescientists.

Onetypeofplanktonthatseemstohavegreatharvestpossibilitiesisatinyshrimplikecreaturecalledkrill.Growingtotwoorthreeincheslong,krillprovidethemajorfoodforthegiantbluewhale,thelargestanimalevertoinhabittheEarth.Realizingthatthiswhalemaygrow100feetandweigh150tonsatmaturity,itisnotsurprisingthateachonedevoursmorethanonetonofkrilldaily.

Krillswimaboutjustbelowthesurfaceinhugeschoolssometimesmileswide,mainlyinthecoldAntarctic.Becauseoftheirpinkcolor,theyoftenappearasasolidreddishmasswhenviewedfromashiporfromtheair.Krillareveryhighinfoodvalue.Apoundofthesecrustaceanscontainsabout460calories—aboutthesameasshrimporlobster,towhichtheyarerelated.

Ifthekrillcanfeedsuchhugecreaturesaswhales,manyscientistsreason,theymustcertainlybecontendersasnewfoodsourceforhumans.

1.Whichofthefollowingbestportraystheorganizationofthepassage?

A.Theauthorpresentstheadvantagesanddisadvantagesofplanktonasafoodsource.

B.Theauthorquotespublicopiniontosupporttheargumentforfarmingplankton.

C.Theauthorclassifiesthedifferentfoodsourcesaccordingtoamountofcarbohydrate.

D.Theauthormakesageneralstatementaboutplanktonasafoodsourceandthenmovestoaspecificexample.

2.Accordingtothepassage,whyisplanktonregardedtobemorevaluablethanlandgrasses?

A.Itiseasiertocultivate.

B.Itproducesmorecarbohydrates.

C.Itdoesnotrequiresoil.

D.Itismorepalatable.

3.Whydoestheauthormention“planktonburgers”?

A.Todescribetheappearanceofonetypeofplankton.

B.Toillustratehowmuchplanktonawhaleconsumes.

C.Tosuggestplanktonasapossiblefoodsources.

D.Tocomparethefoodvaluesofbeefandplankton.

4.Whatismentionedasoneconspicuousfeatureofkrill?

A.Theyarethesmallestmarineanimals.

B.Theyarepinkincolor.

C.Theyaresimilarinsizetolobsters.

D.Theyhavegrasslikebodies.

5.Theauthormentionsallofthefollowingasreasonswhyplanktoncouldbeconsideredahumanfoodsourceexceptthatitis___.

A.highinfoodvalue.

B.inabundantsupplyintheoceans.

C.anappropriatefoodforotheranimals.

D.freeofchemicalsandpollutants.

_____,hewouldnothaverecoveredsoquickly.

Thethreementriedmanytimestosneakacrosstheborderintotheneighboringcountry_____bythepoliceeachtime.

Ineverregretted_____hisoffer,foritwasnotwheremyinterestlay.