The company used 50 percent of the raw materials, the rest of which __________ sent to other cities to help the factories there.

A．is

B．was

C．are

D．were

镗床镗削时刀杆在镗头上装夹是否正确，直接影响到镗削的（）。

A.加工表面粗糙度

B.加工精度

C.加工状况

D.加工质量