—Mrs White, why are you standing here?

—I’m waiting for my son. He ___________ back from school.

A．didn’t come

B．won’t come

C．hasn’t come

D．hadn’t come

完井钻井液的密度、抑制性、造壁性、封堵性能要满足（）的要求。

A.漏失层

B.取心层

C.所钻地层

D.固井