-–Do you think that we should make preparations for the competition in advance?

-–Exactly. ______.

A．Actions speak louder than words

B．Fight no battle unprepared

C．Better late than never

D．A good beginning is half done

镗刀前角的选择主要与（）等因素有关。

A.工件材料

B.镗刀（刀片）材料

C.加工性质

D.加工因素

E.工艺系统刚度

F.加工表面粗糙度