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小颖家离学校1200米,其中有一段为上坡路,另一段为下坡路.她去学校共用了16分...
小颖家离学校1200米,其中有一段为上坡路,另一段为下坡路.她去学校共用了16分钟.假设小颖上坡路的平均速度是3千米/时,下坡路的平均速度是5千米/时.若设小颖上坡用了x分钟,下坡用了y分钟,根据题意可列方程组为( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192706728887544/SYS201311011927067288875013_ST/0.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192706728887544/SYS201311011927067288875013_ST/1.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192706728887544/SYS201311011927067288875013_ST/2.png)
D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192706728887544/SYS201311011927067288875013_ST/3.png)
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