- 問題詳情:Evenifyouareagoodhigh-jumper,youcanjumponlyaboutsevenfeetofftheground.Youcannotjumpanyhigherbecausetheearthpullsyouhard.Thepulloftheearthiscalledgravity.Youcaneasilyfindoutthepulloftheearth.Ifyouweighyourself,youwillknowhowmuchgravityispullin...
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