Thereisverysimplewayofmeasuringtheheightofawater-tower,whichwecannotmeasurebyclimbing.Suppose,forexample,thatwewishtofindouttheheightofthewater-tower,AB,inafactory.Wefirstofallgotowherethewater-toweris

　　Thereisverysimplewayofmeasuringtheheightofawater-tower,whichwecannotmeasurebyclimbing.

　　Suppose,forexample,thatwewishtofindouttheheightofthewater-tower,AB,inafactory.Wefirstofallgotowherethewater-towerisstandingandmeasureadistanceof,say,25feetfromit.Thenwetakeastick,andstanditinthegroundatthespotwehavejustmarked.

　　Letussupposethestickweareusingis4feetinheight.Wenowwalkfartherawayfromthewater–towerinthesamestraightlineaswhenwemeasuredoffthedistanceof25feet.Wegofromthewater-toweruntilwecometopointE,wherewithourheadontheground,weseethetopofthestickandthetopofthewater-towerinthesameheightline---thatis,thetopofthestickjustcoversthehighestpartofthewater-tower.Everyschoolboycanworkouttheheightofthewater-towernow.

　　SupposethatthelineCEisfivefeet.Weknowthatthestickis4feethighandthedistanceBEis30feet.Thus,5isto4as30istoAB.

　　小题1:Ifwewanttoknowhowhighatalltreeis,_______.

　　A.wehavetoclimbupthetree

　　B.wehavenowayout

　　C.wemustcutdownthetree

　　Dweneedn’tclimbupthetree

　　小题2:Accordingtothepassage,whichofthefollowingiscorrect?

　　小题3:Itisclearfromthisthattheproblemcanbesettledby_________.A．achildB．theboywhohaslittleschoolingC．everyoneD．agirlatmiddleschool小题4:Tomeasureawater-towerinthisway,_________.A．notoolisneededB．Besidesastick,tape-measure(卷尺)oratleastarulerisnecessary.C．wehavetousenothingbutastickD．wehavetoprepareasetofexpensivetools