TheextraordinaryEastgateBuildinginHarare，Zimbabwe'scapitalcity，issaidtobetheonlyoneintheworldtousethesamecoolingandheatingprinciplesasthetermitemound（白蚁堆）．ArchitectMickPearceusedpreciselythesamestra

　　TheextraordinaryEastgateBuildinginHarare，Zimbabwe'scapitalcity，issaidtobetheonlyoneintheworldtousethesamecoolingandheatingprinciplesasthetermitemound（白蚁堆）．

　　ArchitectMickPearceusedpreciselythesamestrategywhendesigningtheEastgateBuilding，whichhasnoair-conditioningandalmostnoheating．Thebuilding-thecountry'slargestcommercialandshoppingcomplex-useslessthan10%oftheenergyofaconventionalbuildingofitssize．TheEastgate'sownerssaved3.5millionona36millionbuildingbecauseanair-conditioningplantdidn'thavetobeimported．

　　Thecomplexisactuallytwobuildingslinkedbybridgesacrossashady，glass-roofedatrium（天井）opentotheair．Fanssuckfreshairinfromtheatrium，blowitupstairsthroughhollowspacesunderthefloorsandfromthereintoeachofficethroughbaseboardvents（通风口）．Asitrisesandwarms，itisdrawnoutviaceilingventsandfinallyexiststhroughforty-eightbrickchimneys．

　　Duringsummer'scoolnights，bigfansblowairthroughthebuildingseventimesanhourtocooltheemptyfloors．Byday，smallerfansblowtwochangesofairanhourthroughthebuilding，tocirculatetheairwhichhasbeenincontactwiththecoolfloors．Forwinterdays，therearesmallheatersinthevents．

　　ThisisallpossibleonlybecauseHarareis1600feetabovesealevel，hascloudlessskies，littledampnessandrapidtemperatureswings-daysaswarmas31℃commonlydropto14℃atnight．"Youcouldn'tdothisinNewYork，withitsfantasticallyhotsummersandfantasticallycoldwinters，"Pearcesaid．

　　TheengineeringfirmofOveArup&Partnersmonitorsdailytemperatures．Itisfoundthatthetemperatureofthebuildinghasgenerallystayedbetween23℃and25℃，withtheexceptionoftheannualhotperiodjustbeforethesummerrainsinOctoberandthreedaysinNovember，whenadoorkeeperaccidentallyswitchedoffthefansatnight．Andtheairisfresh-farmoresothaninair-conditionedbuildings，whereupto30%oftheairisrecycled．

　　47．WhywasEastgatecheapertobebuiltthanaconventionalbuilding？___

　　A．Itwasdesignedinasmallersize．

　　B．Noairconditionerswerefixedin．

　　C．Itsheatingsystemwaslessadvanced．

　　D．Itusedratherdiff