[答案]
1.B 2.C 3.A
【解析】
【原文】W:Hi,everyone.Aswearewaitinghere,letmeintroduceCastleHowardtoyou.CastleHowardhasbecomeapopulartouristattractioninrecentyears.Thoughitsnamecontainstheword"castle",itisnotatruecastle,becauseitwasneverusedfordefence.CastleHowardisactuallyanEnglishcountryhouse.IthasbeenhometotheHowardfamilyformorethan300years.Overtheyears,anumberoffilmshavebeenshotthere.Whenyouvisitittomorrow,you'llseemanythings.Perhapsthere'stoomuchtosee,butmakesureyoudon'tmissthesetwothings.First,theWalledGardens.Itisagroupofthreegardens.Youcanfind2,000differenttypesofrosesthere,almostalltypesofrosesinEngland.TheWalledGardensisopeneverydayoftheyear,exceptChristmas.Second,theWoodlandGarden.Itisknownforfloweringplants,fruittreesandpathwaysthroughawoodedsetting.Inaword,CastleHowardisreallybeautiful.Youcouldspendawholedayenjoyingitsbeautytomorrow.
【题干】 Theworldwide20thcentury"GreenRevolution",whichsawhugeyear﹣by﹣yearincreasesinglobalgrainyields(产量),wasfueledbythedevelopmentinthe1960sofnewhigh﹣yieldingdwarfed(矮小)varietiesknownasGreenRevolutionVarieties(GRVs).
ThesedwarfedGRVsarecommonallovertheworldintoday'swheatandricecrops.Becausetheyaredwarfed,withshortstems,GRVsdevoterelativelymoreresourcesthantallplantstothegrowthofgrainsratherthanstems,andarelesslikelytosufferyieldlossesfromwindandraindamage.However,thegrowthofGRVsrequiresfarmerstouselargeamountsofnitrogenfertilizers(氮肥)intheirfields.Thesefertilizersarecostlytofarmersandcauseextensivedamagetothenaturalenvironment.ThedevelopmentofnewGRVscombininghighyieldswithreducedfertilizerrequirementsisthusaglobalagriculturalgoal.
ResearchersattheUniversityofOxfordandtheChineseAcademyofSciencehavediscoveredforthefirsttimeagenethatcanhelpreachthegoal.Comparing36differentdwarfedricevarieties,theresearchersidentifiedanovelnaturalgenethathelpsincreasetherateatwhichplantsmakeuseofnitrogenfromthesoil.Thisgene,calledGRF4,canincreasetheamountofaprotein(蛋白质)inplantcells.GRF4isactuallyapromoterthatencouragestheactivityofothergenes—genesthatpromotenitrogenuptake(摄入).ProfessorHarberdsaid,"IncreasingGRF4levelscouldcontributetoanincreaseinthegrainyieldsofGRVs,especiallyatlowfertilizerinputlevels."
TheresearcherssaythelatestricevarietycontainingGRVsshouldnowbecomeamajortargetforfarmersinincreasingcropyieldsandfertilizeruseefficiency,withtheaimofachievingtheglobalgrainyieldincreasesnecessarytofeedagrowingworldpopulationatareducedenvironmentalcost.Itisveryurgentatthemoment.
ProfessorHarberdadded,"Thisstudyisanexampleofhowstudyingfundamentalscienceobjectivescanleadrapidlytopotentialsolutionstoglobalchallenges.Itshowshowthediscoverycanenablechancesforfoodsecurityandfuturenewgreenrevolutions."
(1)WhatcanweknowaboutdwarfedGRVs? B
A.Theyhavehigheryieldandtallerstems.
B.Theyarea"double﹣edgedsword".
C.Theyareenvironmentallyfriendly.
D