unit 5 look into science lesson 27 planet danny 习题2

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1、UNIT5LookintoScienceLesson27PlanetDanny习题2一、阅读理解（一）ALegWalkingRightHerearesomesigns+-x…,thesignsareverydifferent.Theymeanverydifferentthings.Whenyouseethem,youknowwhattodo.Thissign+meansthatyouwilladdsomenumerals.Thissign—meansthatyouwilltakeonenumeralawayfromanother.Youwillsubt

2、ract（减去）.Whatwillyoudowhenyouseexand…?Oursignsareeasytoread.Theyareeasysignstoremember.Lookatthesetwosigns….TheancientEgyptiansusedthesesigns.Apictureofalegwalkingtothelefttoldthemtoaddsomenumerals.Apictureofalegwalkingtotherighttoldthemtosubtract.Inthe1500speopleusedthisprinted

3、（印刷的）sign&toaddnumerals.Afterawhilethesignbegantolooklikethis….Later,thesignbecame+.Howmuchis2…2?1.Whatdoyoudowhenyouseethissign+?A.WalkawayB.WriteanumeralC.ReadasignD.Add2.Thewordinthestorythatmeanstotakeonenumeralawayfromanotheris_____.3.Thestorysays,“Oursignsareeasytoread.The

4、yareeasysignstoremember”.Thewordtheymeans______.4.Whichofthefollowingdoesthisstoryleadtobelieve?A.EgyptianscouldnotaddnumeralstogetherB.AllEgyptianshadtwoleftlegs.C.Oursignsarenothardtounderstand5.Whatdidthesigntoaddnumeralsbegintolooklike(whichsentenceisexactlyliketheoneinyourb

5、ook)?A.Afterawhile,thesignbegantolooklikethis….B.Afterawhile,thesignbegantolooklikethis+.C.Afterawhile,thesignbegantolooklikethis&.6.Themainideaofthewholestoryisthat______.A.thesignsforaddingandsubtractinghavechanged.B.Peoplecouldnotwriteinthe1500sC.theoldsignsweregoodforEgyptia

6、nsbutnotforusKey:1.D2.substract3.signs4.C5.A6.A(二)Mexico'sneighboursaretheUnitedStatestothenorthandGuatemalaandBelizetothesouth.MexicoisaboutonequarterofthesizeoftheUnitedStates.Mexicohasmorethanninetymillionpeople.ThelanguageofMexicoisSpanish.ThismakesMexicotheworld'slargestSpa

7、nish-speakingcountry.MexicoCityisthecapitalandlargestcityofMexico.Thecityisalsoveryhigh.Itis7349feethigh(2240metres).Thismakesitoneofthehighestcapitalcitiesintheworld.Thepopulation,ofMexicoCitygrowsbiggereveryday.Aboutthirtymillionpeoplelivethere.Ithasmorepeoplethananyothercityi

8、ntheworld,evenmorethanTokyo.Mexicoalsohasitsspe