长方形底面积=0.8*0.25=0.2米2125L水=0.125米3则 H=0.125/0.2=0.625米=6.25分米
宽25cm=0.25m，0.8*0.25=0.2m ， 125升=125立方分米，0.2m=2dm，125/2=62.5dm
