Oceanographyhasbeendefinedas"Theapplicationofallsciencestothestudyofthesea"Beforethenineteenthcentury,scientistswithaninterestintheseawerefewandfarbetween.CertainlyNewtonconsideredsometheoreticalaspectsofitinhiswritings,buthewasreluctanttogotoseatofurtherhiswork.
Formostpeopletheseawasremote,andwiththeexceptionofearlyintercontinentaltravelersorothers,whoearnedalivingfromthesea,therewaslittlereasontoaskmanyquestionsaboutit,letalonetowhatlaybeneaththesurface,Thefirsttimethatthequestion"Whatisatthebottomofoceans"？hadtobeansweredwithanycommercialconsequencewaswhenthelayingofatelegraphcablefromEuropetoAmericawasproposed.Theengineershadtoknowthedepthprofile（轮廓）oftheroutetoestimatethelengthofcablethathadtobemanufactured.
ItwastoMauryofUSNavythattheAtlanticTelegraphCompanyturned,in1853,forinformationonthismatter.Inthe1840s,Mauryhadbeenresponsibleforencouragingvoyagesduringwhichsoundings（试探）weretakeninvestigatethedepthsoftheNorthAtlanticandPacificOceans.Later,someofhisfindingsarousedmuchpopularinterestinhisbookThePhysicalGeographyoftheSea.
Thecablewaslaid,butnotuntil1866wastheconnectionmadepermanentandreliable.Attheearlyattempts,thecablefailedandwhenitwastakenoutforrepairsitwasfoundtobecoveredinlivinggrowths,afactwhichdefiedcontemporaryscientificopinionthattherewasnolifeinthedeeperpartsofthesea.
Withinafewyearsoceanographywasunderway.In1872Thomsonledascientificexpedition,whichlastedforfouryearsandbroughthomethousandsofsamplesformthesea.Theirclassificationandanalysisoccupiedscientistsforyearsandledtoafive-volumereport,thelastvolumebeingpublishedin1895.
Thispassageismainlyabout_____________.
A）thebeginningsofoceanography
B）thelayingofthefirstunderseacable
C）theinvestigationofoceandepths
D）theearlyintercontinentalcommunications
本题问及全篇的中心思想。通过快读（skimming）我们知道这是一篇叙述"海洋学"的文章。第一段谈的是关于"海洋学"的定义；第二段是讲19世纪前对海洋感兴对趣的科学家不多；第三段谈到由于有人提了铺设海底电缆,人们才开始研究"海底深处究竟是什么"；第四段说Maury考察北大西洋和太平洋的发现引起广泛的注意；第五段讲修筑海底电缆过程中发现大量的海洋生物；最后一段是海洋学研究的成果。可风全篇主要是讲海洋学的研究是如何开展起来的,所以正确答案是A）。文章有个地方谈到铺设义；第二段是讲19世纪前对海洋感兴趣的科学家不多；第三段谈到由于有人提出铺设海底电缆,人们才开始研究"海底深处究竟有什么"；第四段说Maury考察北大西洋和太平洋的发现引起广泛的注意；第五段讲修筑海底电缆过程中发现大量的海洋生物；最后一段是海洋学研究的成果。可见全篇主要是讲海洋学的研究是如何开展起来的,所以正确答案是A）。文章有好几个地方谈到铺设海底电缆B）和越洋通讯（D）,但都是围绕着海洋学这条主线的。至于C）,测量海洋深度,只是一个细节,不可能是文章的中心意思。
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