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英语Our teacher told us not to spend much time on playing.

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英语Our teacher told us not to spend much time on playing.
甲乙两地相距140KM,一船在两地间航行,顺流用了7h,逆流用了10h,则这艘船在静水中的速度是( ),水流速度是( )
英语:We were told not to spend much time on playing by our teacher.
数学:设船在静水中的速度为v1,水的速度为v2
那么:140/(v1+v2)=7
140/ (v1-v2)=10
解方程组可得:v1=17km/h v2=3km/h
v1+v2为顺水速度;v1-v2为逆水速度