单项选择题
A.11~14L/s•m2,9~7minB.12~15L/s•m2,7~5minC.13~16L/s•m2,8~6minD.16~17L/s•m2,7~5min
A.滤层各点的水头损失保持不变B.水头损失与杂质在滤层中的分布无关C.水头损失由上到下递减D.起始水头损失大小与过滤时间无关
A.20B.15C.10D.5