_____the film so many times , I don’t need to see or hear it___what is happening now on the screen .

A．Seeing ; knowing

B．Having seen ; to know

C．To have seen , to know

D．To see , to know

离心式耐腐蚀泵均为( )结构。

A．两极单吸悬臂式

B．单极单吸悬臂式

C．两极双吸悬臂式

D．单极双吸悬臂式