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wsdoll

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发表于 2007-9-7 12:22:00 | 显示全部楼层

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68、A,B两地相距250英里，X,Y两列火车分别同时从两地相向开出，2小时后相遇。问相遇时哪辆火车离终点近。
(1)Before the two train met with each other,the X had averaged a speed of 50 miles per hour.
(2)The Y train averaged a speed of 50 miles per hour for the entire trip.

答案是A,

为什么B不行。 the entire trip是指Y和X相遇后，还继续向A地开吗？