A.1-1/2*(50.6-50) B.1-1/2*(50.6-0.6) C.1-1/3*(50.6-50)/2 D.1-1/2*(50.6-50)/3
A.180 B.184 C.183 D.182
A.地槽 B.高位槽 C.中間槽 D.濾機(jī)