Hardly ____ the airport when the plane took off.

A．I had arrived at　

B．had I arrived

C．had I reached　

D．I had got to

水压试验时，当排气管（）时，关闭放气阀和低压水封闭阀。

A、排出大气流

B、排出水柱

C、排出大水点

D、排出小气流