在制作图象映射时，可以

Thefoodweeatseemstohaveprofoundeffectsonourhealth.Althoughsciencehasmadeenormousstepsinmakingfoodmorefittoeat,ithas,atthesametime,mademanyfoodsunfittoeat.Someresearchhasshownthatperhapseightypercentofcancerisrelatedtothedietaswell,especiallycancerthecolon.Differentculturesaremorepronetocontractcertainillnessesbecauseofthefoodthatischaracteristicinthesecultures.Thatfoodrelatedtollnessisnotanewdiscovery.In1945,governmentresearchersrealizedthatitratesandnitrites,commonlyusedtopreservecolorinmeats,andotherfooddditives,causedcancer.Yet,thesecarcinogenicadditivesremaininourfood,nditbecomesmoredifficultallthetimetoknowwhichthingsonthepackginglabelsofprocessedfoodarehelpfulorharmful.Theadditiveswhichweeatarenotallsodirect.Farmersoftengivepenicillintobeefandpoultry,andbecauseofthis,penicillinhasbeenfoundinthemilkoftreatedcows.Sometimessimilardrugsareadministeredtoanimalsnotformedicinalpurposes,butforfinancialreasons.Thefarmersaresimplytryingtofattentheanimalsinordertoobtainahigherpriceonthemarket.AlthoughtheFoodandDrugAdministration(FDA)hastriedrepeatedlytocontroltheseprocedures,thepracticescontinue.

48.Whatisthemaintopicofthepassage?

A.Foodandourhealth

BFoodandadditives

C.Foodandcancer

DFoodandculture

49AllofthefollowingstatementsaretrueEXCEPT_______.

AFortypercentofcanceriscausedbyproblemsrelatedtofood.

BResearchershaveknownaboutthepotentialdangeroffoodadditivesformanyyears

C.Weeatsomeofthefoodadditivesdirectlyandsomeindirectly

DDrugsarealwaysgiventoanimalsformedicinalpurposes

50.Whydofarmersgivedrugstotheiranimals?

A.tospeedupthegrowthofanimals

BTomaketheanimalsfatter

Ctomaketheanimals’meatfittoeat

DTomaketheanimals’meatrichinnutrients

51.Itcanbeinferredfromthepassagethat_________.

Ascientisthavemadeallthefoodfittoeat

Bonlyinrecentyearshavepeoplefoundthatthefoodisrelatedtoone’sillness

Callkindsofcancerarerelatedtothediet

Dsomeadditivesareharmfultoourhealth

52.Theword“this”inthesecondsentenceofparagraph2mostprobablyrefersto__________.

Afarmer

Bpenicillin

Cbeefandpoultry

Dthefactthatfarmersoftengivepenicillintoabeef

在photoshop中有哪几种锁定图层功能

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

截流日期应选择在()。