---It’s said that Williams will come to help us.

---       we depend on him, we have to do most of the work ourselves.

A．No matter what

B．However much

C．Whatever

D．However

克服水流阻力以维持液体的运行时，单位重量的液体所损失有能量称为水头损失。可分为（）。

A.沿程水头损失

B.主管水头损失

C.支管水头损失

D.局部水头损失