Somepeopleliketoliveinhouseofthepast.Theymaychoosetoliveinawoodenhouse.Theysaytheseofhousesareeasytobuildandwarminwinter.Othersliketoliveinhousesofthefuture.Theymayliveinahousewhichgetsitsenergyfromthesun.Afewotherpeopleliketoliveinhousesthathavecharacteristics(特征)ofboththepastandfuture.Thesepeoplemayliveinahouseundertheground.Manypeoplethinkundergroundhousesarecoldanddark,butthatisnottrue.Thesehouseshavespecialwindowsintherooforlargewindowsononeside.Thesewindowsgivethehousesalotoflight.Theideaofundergroundhousesisveryold.PeopleinthepastlivedinundergroundhousesandundergroundcitiesinChina,JapanandCanada.Somecountriesalsobuildundergroundfactoriesandstore-houses(仓库)toholdthings.Intheunitedstates,morepeoplearebeginningtobuildundergroundhousessincetheysaveopenlandforparks,gardensandsportfields.Undergroundhousesalsosaveenergy.Theyuseonlyalittleenergytostaywarmorcool.Ownersofthesehouseslikethem.JohnBoardisanarchitect(建筑师)whobuiltanundergroundhouseinNewYork.Hiswife,Barbaraisanoutdoorperson,butshelikesherundergroundhome.“It’sperfect.Iloveit.”shesays.31.Oneexampleofhousesofthepastis______houses.