阅读理解
Everyobjecthasweight.ButthecenterofitsweightisnotalwaysinthemiddleoftheobjectIfthetopofanobjectisheavierthanitsbottomitwillfallovereasily.Wesaythatitscenterofgravity(引力)ishigh.Butifthebottomisheavieritwon'tfalleasily.Thenwesaythatitscenterofgravityislow.
Lookatthefirstpictureliftsemptyboxmustfalloverbemuseitscenterofgravity(C)isnotabovethelineofitsbottom(AB).
Nowlookatthesecondpicture.Thereissomeheavyironatthebottomofthisbox.Itwillnotfallbecauseitscenterofgravityisaboveitsbottom.
(1)Pleasepointoutwhichboxwillnotfall?
(2)FromthepassagewecaninferthattheLeaningTowerofPisadoesnotfallisbecause_______.
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A.thetopofthetowerisheavierthanitsbottom
B.thebottomofthetowerisnotheavierthanitstop
C.itscenterofthegravityisstillabovethelineofitsbottom
D.itscenterofthegravityisnotabovethelineofitsbottom
(3)Ifanobjecthasalowcenterofgravity_______.
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B.itwon'tfalleasily
D.itstopmustbeheavier
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A.Thecenteroftheweightisalwaysinthemiddleoftheobject
B.Thecenteroftheweightisalwaysontheobject
C.Thecenterofgravityisnotalwaysinthemiddleoftheobject
D.Thecenterofthegravityisalwayshigh
(5)Thepassageismainlyabout_______.
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