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.achild |
B.theboywhohaslittleschooling |
C.everyone |
D.agirlatmiddleschool |
小题4:Tomeasureawater-towerinthisway,_________.
A.notoolisneeded |
B.Besidesastick,tape-measure(卷尺)oratleastarulerisnecessary. |
C.wehavetousenothingbutastick |
D.wehavetoprepareasetofexpensivetools |