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Thereisverysimplewayofmeasuringtheheightofawater-tower,whichwecannotmeasurebyclimbing.Suppose,forexample,thatwewishtofindouttheheightofthewater-tower,AB,inafactory.Wefirstofallgotowherethewater-toweris
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问题描述:

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.notoolisneededB.Besidesastick,tape-measure(卷尺)oratleastarulerisnecessary.C.wehavetousenothingbutastickD.wehavetoprepareasetofexpensivetools

彭岩回答:
  小题1:D小题2:A小题3:D小题4:C   
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