阅读理解,阅读下面四篇材料,根据其内容,选择正确答案或完成阅读任务。
Oneofthemostinterestingprojectsinoceanography(海洋学)istheworkofmappingtheoceanfloor.Onlyaverysmallpartofithasbeenmapped.Thiswasnotimportantwhenonlysurfaceshipssailedtheworld’soceansbutitcanmeanthedifferencebetweenlifeanddeathtomeninsubmarines(潜艇).
Longagotherewasonlyonewaytofindouthowdeeptheoceanwas.Aseamancouldthrowaweightedropeoverthesideofhisship.Thenhepulledtheropeupafterithadreachedthebottom.Butthiswasnotaveryexactwayofmeasuring.
Inthetwelfthcenturyabetterwaywasfound.Soundwasusedtomeasuretheocean.AnAmericanNavyshipsailedtheoceantomakeanexperiment.Seamendroppedanumberofdevicesthatwouldgiveoutaloudnoisewhentheyhitthebottom.Andadevicehadbeeninventedmeasuredthetimeittookforthesoundtoreachtheship.Ithelpedoceanographermaptheoceanfloor.
Underwaterphotographyisalsoimportantinmappingpartsoftheoceanfloor.Withthenewmethodsthathavebeenperfectedcamerascantakepicturesoftheunderwatervalleysevenincolor.
1.Mappingtheoceanflooristhemostimportanttopeople__ .
A.onships B.inboats C.inthesea D.insubmarines
2.Whichwaywasusedtomeasurethedepthoftheoceaninthepast?
A.Usingaweightedrope B.Usingaseaman
C.Usingaboat D.Usingsound
3.Whatdidtheseamenusewhentheydidtheexperiment?
A.Stones B.Instruments C.Devices D.Ropes
4.Wecanknowfromthelastparagraphthat_.
A.cameraistheonlyperfectwayofmappingtheoceanfloor.
B.camerawilltaketheplaceofanyotherinstrument.
C.cameracanmapanypartoftheoceanfloor.
D.cameraisoneofthenewwaystomaptheoceanfloor.
5.Howmanywayshavebeenusedtomaptheoceanfloor?
A.Two B.Three C.Four D.F