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1、ReadingComprehensionDirections:Inthissectiontherearefivepassagesfollowedbyfifteenquestionsorunfinishedstatements,eachwithfoursuggestedanswermarkedA,B,CandD. Choosetheonethatyouthinkisthecorrectanswer.TEXTAPetroleumproducts,suchasgasoline,kerosene,homeheatingoil,residualfueloil,andlubricating
2、oils,comefromonesource--crudeoilfoundbelowtheearth'ssurface,aswellasunderlargebodiesofwater,fromafewhundredfeetbelowthesurfacetoasdeepas25,000feetintotheearth'sinterior. Sometimescrudeoilissecuredbydrillingaholethroughtheearth,butmoredryholesaredrilledthanthoseproducingoil. Pressureatthesou
3、rceorpumpingforcescrudeoiltothesurface. Crudeoilwellsflowatvaryingrates,fromtentothousandsofbarrelsperhour. Petroleumproductsarealwaysmeasuredin42-gallonbarrels.Petroleumproductsvarygreatlyinphysicalappearance:thin,thick,transparentoropaque,butregardless,theirchemicalcompositionismadeupoftw
4、oelements:carbonandhydrogen,whichformcompoundscalledhydrocarbons. Otherchemicalelementsfoundinunionwiththehydrocarbonsarefewandareclassifiedasimpurities. Traceelementsarealsofound,buttheseareofsuchminutequantitiesthattheyaredisregarded. Thecombinationofcarbonandhydrogenformsmanythousandsof
5、compoundswhicharepossiblebecauseofthecariouspositionsandjoiningsofthesetwoatomsinthehydrocarbonmolecule.Thevariouspetroleumproductsarerefinedfromthecrudeoilbyheatingandcondensingthevapors. Theseproductsaretheso-calledlightoils,suchasgasoline,kerosene,anddistillateoil. Theresidueremainingaft
6、erthelightoilsaredistilledisknownasheavyorresidualfueloilandisusedmostlyforburningunderboilers. Additionalcomplicatedrefiningprocessesrearrangethechemicalstructureofthehydrocarbonstoproduceotherproducts,someofwhichareusedtoupgradeandincreasetheoctaneratingofvarioustypesofgasoline.1.Whichofth
7、efollowingisNOTtrue?A.Crudeoilisfoundbelowlandandwater.B.Crudeoilisalwaysfoundafewhundredfeetbelowthesurface.C.Pumpingandpressureforcecrudeoiltothesurface.D.Avarietyofpetroleumproductsisobtainedfromcrudeoil.2.Manythousandsofhydrocarboncompoun
