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.
练习题：
Choosecorrectanswerstothequestion:
1.WhatdoweknowaboutLegionnaire'sdiseasefromthepassage?
A.Itwasthemostwidelyconcernedofficehazard.
B.Itcanaffectpeoplebothinsideandoutsidethebuilding.
C.Ithappensonlyinair-conditionedofficebuildings.
D.Itdoesnotdevelopinwell-designedbuildings.
2.Intheoldair-conditionedsystems,bacteriafirstdevelop______.
3.Thefactthatabouthalfofworkersdevelopedtheabilitytofightoffthebacteriamay__.
A.relievepeople’sworryaboutthedangercausedbythebacteria
B.helppeoplefindaneffectivewaytogetridofthebacteria
C.reflecttheseriousdangerbroughtbythebacteria
D.causeseriousdiseasesuchascancerstopeople
4.Theauthormostprobablywantsthereaderstotreatbiocideswithanattitudeof_.
5.Thelastparagraphimpliesthatourimmunesystemcanbeweakenedwhen_•
A.weliveinanartificialclimaticenvironment
B.therearevariationsintemperatureandhumidity
C.ourbodytemperaturesoftenremainnothighenough
D.weareoftenexposedtodiseasessuchascoldsandflu
1.[B]事实细节题。本题主要考査复合句的理解。第2段最后一句表明B是正确选项。选项A中的most和C中的only都太绝对了，文中并未对选项A和C中的相关说法加以这样的限定。选项D也太绝对了，第2段第3句只是说到“大多数情况下是因为空调设计欠佳所致”,并不是说所有设计良好的大厦就不会发生这种情况。
2.[A]事实细节題。本题考查复合句的理解。只要明白第3段第2句这个非限制性定语从句中的thebottomsofwhich中的which是指上文的reservoirs,问题就不难解决了。
3.[C]事实细节题。本题考查被动语态长句的理解。在第3段第3句中，关键词是highlight,选项C是对原句主谓部分的近义替换。选项A和B在文中皆无提及，选项D是过度使用生物杀灭剂的后果，与本题干的情况无关。
4.[A]观点态度题。第3段最后两句讨论生物杀灭剂的用处，其中最后一句中的but,dangerous和cancers等词说明作者认为要慎用这种杀灭剂。作者并没对杀灭剂全盘否定，只是说过量使用会引发危险，因此选项D不对。
5.[C]推理判断題。本题考查代词的理解。解题的关键在于理解最后一句中的This是指上一句所说的情况。选项A中所说的人造环境不是使免疫系统变弱的必然条件。选项B是保持免疫系统健康的条件。选项D是免疫系统变弱后的影响。
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