Modernscientistsdividetheprocessofdyingintotwostages—clinicalor(emporarydeathandbiologicaldeath.Clinicaldeathoccurswhenthevitalorgans,suchastheheartorlungs,haveceasedtofunction,buthavenotsufferedpermanentdamage.Theorganismcanstillberevived(复活).Biologicaldeathoccurswhenchangesintheorganismleadtothedisintegration(解体)ofvitalcellsandtissues.Deathisthenirreversibleandfinal.
Scientistshavebeenseekingawaytoprolongtheperiodofclinicaldeathso(hattheorganismcanberevivedbeforebiologicaldeathoccurs.Thebestmethoddevelopedsofarinvolvescoolingoftheorganism,combinedwithnarcotic(麻醉的)sleep.Byslowingdownthebody'smetabolism(新成代谢),coolingdelaystheprocessesleadingtobiologicaldeath.
Toillustratehowthisworks,scientistsperformedanexperimentonasix-year-oldfemalemonkeycalledKeta.ThescientistsputKetatosleepwithanarcotic.Thentheysurroundedherbodywithice-bagsandbegancheckingherbodytemperature.Whenithaddroppedto28degreesthescientistsbegandrainingbloodfromanitsbody.Themonkey'sbloodpressuredecreasedandanhourlaterboththeheartandbreathingstopped;clinicaldeathsetin.FortwentyminutesKetaremainedinthisstate.Hertemperaturedroppedto22degrees.Atthispointthescientistspumpedbloodintoitsbodyinthedirectionoftheheartandstartedartificialbreathing.Aftertwominutesthemonkey'sheartbecameactiveoncemore.Afterfifteenminutes,spontaneousbreathingbegan,andafterfourhoursKetaopenedhereyesandliftedherhead.Aftersixhours,whenthescientiststriedtogiveherapenicillininjection,Ketaseizedthesyringeandranwithitaroundtheroom.Herbehaviordifferedlittlefromthatofahealthyanimal.
26.Thispassagefocuseson_______.
A.thedifferencebetweenbiologicalandclinicaldeath.
C.prolongingtheperiodofclinicaldeath
D.thenatureofclinicaldeath
27.Thebeststatementofthemainideaofthispassageisthat_______.
A.modemscientistsdividetheprocessofdyingintoclinicalandbiologicaldeath
B.biologicaldeathoccurswhenvitalorganshavesufferedpermanentdamage
C.scientistshavefoundawaytoprolongtheperiodofclinicaldeath
D.coolingdelaystheprocessesleadingtobiologicaldeath
28.Onecharacteristicofclinicaldeathis______.
A.lastingdamagetothelungsB.destructionofthetissues
C.temporarynon-functioningoftheheartD.thattheorganismcannotberevived
29.Accordingtothepassage,coolinganorganism_______.
A.speedsupthebody'smetabolismB.slowsdisintegrationofbodytissues
C.preventsdamagetoorgansD.revivesdamagedorgans
30.Onepossiblebenefitoftheexperimentdiscussedinthepassageis______.
A.lesscrowdedcitiesB.victoryoverdeath
C.protectionagainstfatalinjuryD.fewerdeathsfromheartattacks
