PassageOneQuestions1to5arebasedonthefollowingpassage.Questions46to50arebasedonthefollowingpassage.Textbooksrepresentan11billiondollarindustry,upfrom$8billionin2014.TextbookpublisherPearsonisthelargestpublisher—ofanykind—intheworld.Itcostsabout$1milliontocreateanewtextbook.Afreshmantextbookwillhavedozensofcontributors,fromsubject-matterexpertsthroughgraphicandlayoutartiststoexpertreviewersandclassroomtesters.Textbookpublishersconnectprofessors,instructorsandstudentsinwaysthatalternatives,suchasOpenE-TextbooksandOpenEducationalResources,simplydonot.Thisconnectionhappensnotonlybymeansofcollaborativedevelopment,reviewandtesting,butalsoatconferenceswherefacultyregularlydecideontheirtextbooksandcurriculaforthecomingyear.Itistruethattextbookpublishershaverecentlyreportedlosses,largelyduetostudentsrentingorbuyingusedprinttextbooks.Butthiscanbechalkeduptotheexorbitantcostoftheirbooks—whichhasincreasedover1,000percentsince1977.Areshufflingofthetextbookindustrymaywellbeinorder.Butthisdoesnotmeantheendofthetextbookitself.WhiletheymaynotbeasdynamicasaniPad,textbooksarenotpassiveorlifeless.Forexample,overthecenturies,theyhavesimulateddialogueinanumberofways.From1800tothepresentday,textbookshavedonethisbyposingquestionsforstudentstoanswerinductively.Thatmeansstudentsareaskedtousetheirindividualexperiencetocomeupwithanswerstogeneralquestions.Today’spsychologytexts,forexample,ask:“Howmuchofyourpersonalitydoyouthinkyouinherited?”whileonesinphysicssay:“Howcanyoupredictwheretheballyoutossedwillland?”Expertsobservethat“textbookscomeinlayers,somethinglikeanonion.”Fortheactivelearner,engagingwithatextbookcanbeaninteractiveexperience:Readersproceedattheirownpace.They“customize”theirbooksbyengagingwithdifferentlayersandlinkages.Highlighting,Post-Itnotes,dog-earsandothertechniquesallowforfurthercustomizationthatstudentsvalueinprintbooksoverdigitalformsofbooks.47.Whatisthemaincauseofthepublishers’losses?
Althoughmanyofusmayfeelair-conditionersbringrelieffromhot,humidorpollutedoutsideair,theyposemanypotentialhealthhazards.Muchresearchhaslookedathowthemovementofairinsideaclosedenvironment---suchasanofficebuilding---canspreaddiseaseorexposepeopleinthebuildingtoharmfulchemicals.OneofthemorewidelypublicizeddangersisthatofLegionnaire’sdisease,whichwasfirstrecognizedinthe1970s.Thiswasfoundtohaveaffectedpeopleinbuildingswithair-conditioningsystemsinwhichwarmairpumpedoutofthesystem’coolingtowerswassomehowsuckedbackintotheairintake(通风口),inmostcasesduetopoordesign.Thewarmair,filledwithbacteria,wascombinedwithcooled,conditionedairandwasthencirculatedaroundvariouspartsofthebuilding.Studiesshowedthatevenpeopleoutsidesuchbuildingswereatriskiftheywalkedpastairexhaustpipes.Largeair-conditioningsystemsaddwatertotheairtheycirculatebymeansofhumidifiers(湿度调节器).Inoldersystems,thewaterusedforthisprocessiskeptinspecialreservoirs,thebottomsofwhichprovidebreedinggroundsforbacteriawhichcanfindtheirwayintotheventilation(通风)system.Therisktohumanhealthfromthissituationhasbeenhighlightedbythefactthattheimmunesystems(免疫系统)ofapproximatelyhalfofworkersinair-conditionedofficebuildingshavedevelopedtheabilitytofightofftheorganismsfoundatthebottomofsystemreservoirs.Butchemicalscalled“biocides”areaddedtoreservoirstomakethemgerm-free,andtheyaredangerousintheirownrightinsufficientquantities,astheyoftencontaincompoundsstronglylinkedtocancers.Finally,itshouldbepointedoutthattheartificialclimaticenvironmentcreatedbyair-conditionerscanalsoaffectus.Inanaturalenvironment,whetherindoororoutdoor,therearesmallvariationsintemperatureandhumidity.Indeed,thehumanbodyhaslongbeenaccustomedtothesenormalchanges.Inanair-conditionedlivingorworkingenvironment,however,bodytemperaturesremainwellunder37℃,ournormaltemperature.Thisleadstoaweakenedimmunesystemandthusgreaterexposuretodiseasessuchascoldsandflu.Thefactthatabouthalfofworkersdevelopedtheabilitytofightoffthebacteriamay__.