【Ofalltheproblemsfacingmodernastronomers，perhapsthemostfascinatingis："Canintelligent（有智能的）lifeexistelsewhere？"SincetheEarthisanunimportantplanetmovingroundanunimportantstar，itwouldbeaprideon】

　　Ofalltheproblemsfacingmodernastronomers，perhapsthemostfascinatingis："Canintelligent（有智能的） lifeexistelsewhere？"SincetheEarthisanunimportantplanetmovingroundanunimportantstar，itwouldbeaprideonourparttosupposethatwearetheonlyintelligentbeingsintheuniverse．Buttoobtainproofisdifficult．

　　Themaintroubleisthatourneighborworlds，thebodiesinthesolarsystemappeartobeunsuitableforadvancedlifeforms．TheMoonmayberuledoutatonce； ithashardlyanyatmosphere．Venus（金星） islittlebetter； thesurfacetemperatureisextremelyhighandtheatmosphereismostlycarbondioxide．Mars（火星） withaverythinatmosphereandasevereshortageofwater，maywellsupportsimpleplantlifebutthereseemsnohopeoffindinganimals，whiletheattractiveMartiansofthestory-tellershavelongsincebeengivenup．

　　OfcoursethishasnotstoppedtheflowofbrightideasforcommunicatingwiththesupposedpeopleonMars．IntheearlynineteenthcenturythegreatmathematicianGausssuggestedplantingtree-patternsinSiberia，sothattheMartianswouldseethemandreplaysuitably．Followingupthisidea，theAustrianscientistKarlLittrowproposeddiggingverywideditches（沟） intheSahara，triangularinpatterns，andthenfillingthemwithpetrolorsomesubstancesothat，whenlit，theditcheswouldpresentMartianobserverswitha"flamingtriangle"whichwouldshowtheexistencehereofintelligentminds．EvenbetterweretheplansofCharlesCross，aFrenchwriterofthe1870's，whowantedtobuildalargemirrortoreflectthesun'sraysandconcentratethemonthesurfaceofMars，therebymakingavastburning-glass．Byswingingthemirroraround，CrossexplaineditwouldbepracticabletowritewordsintheMartiandesertssimplybyburningthesand．Formanyyearshebombarded （鼓吹） theFrenchgovernmentwithliteratureaboutthisplanandwasverydisappointedwhennoofficialinterestwasshown．

　　48．Fromthepassagewecanlearnthattheopinionofthewriteristhat___．

　　A．peopleontheeartharealmostcertainlytheonlyintelligentbeingsintheuniverse

　　B．peopleontheeartharedefinitelytheonlyintelligentbeingsintheuniverse

　　C．theremaybeotherintelligentbeingsintheunivers