en ,说的就是您 Working alone at its own constant rate,a machine seals K cartons in 8 hours and working alone at its own constant rate,a second machine seals K cortons in 4 hours.If the two machines,each working at its own constant rate and for the same period of time,togher sedled a certain number of cartons what percent of the cartons were sealed by the machine working at the faster rate. A 25% B33又 3/1 C50% D66 又3/2 Ｅ７５％ 如无意外是选D 不要拿笔 你意念一下 （1）8小时那个家伙比4小时那个家伙效率低 （2）慢家伙速度：快家伙速度=1：2 所以快家伙占2/3 -- by 会员 francineivy (2009/11/5 15:52:23)
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发表于 2010-7-27 13:37:30
