下列哪个滤镜可以减少渐变中的色带（）
下面的描述哪些是正确的：
Inthepast,operationsweredifficult.Untilthemiddleoftheeighteenfifties,surgerywasverydangerous.Manypatientsdiedaftereventhesmallestoperations.Thiswasbecausebacteriaenteredthecutsinthepatientsbodied’andstartedinfection.Insomecountries,upto90percentofpatientsdiedfrominfectionafteroperations.In1865,however,JosephLister,aBritishsurgeon,foundananswertotheproblem.Heusedan“antisepticduring”andafteroperations.Thiskilledthedangerousbacteriaandmostofhispatientslived.Sincethen,surgeonshaveusedantisepticsinalloperations.SurgeryhasdevelopedinmanyimportantwayssincethedayofJosephLister.Today,whenpatientsgotohospitalforanoperation,theycanexpectthebesttreatment,incleanandhygienicconditions.
33.Operationsweredifficultanddangerousuntil_______.
A.1850
B.themiddleof1850
C.themiddleofthefiftiesoftheeighteenthcentury
D.themiddleofthefiftiesofthenineteenthcentury
34.Inthepassage,surgerymeans__________.
A.Theperformingofanoperation
B.cure
C.treatment
D.medicine
35.Inthepast,upto90percentofpatientsdiedafteroperationsmainlyb
ecause__________.
A.bacteriaenteredthecutsinthepatientsbodies’andinfectiontookplace
B.theconditionsinhospitalswerebad
C.theskillofsurgeonswasnotsogood
D.therewerenogoodmedicineatthattime
36.Whichtopicofthefollowingbestsuitsthepassage?
A.Operationsweredifficultinthepast
B.ThedevotionofJosephListertomedicalscience
C.Surgeryhasbecomesafer
D.Developmentsinsurgery
37.JosephListerwas________.
A.aFrenchman
B.aGerman
C.anEnglishman
D.anAmeric