A．He used a glass bowl.

B．He applied a small amount of electricity.

C．The director gave him an idea.

D．He edited the pictures and put them together later.

铣削锥齿轮时，若（）会产生齿向误差和齿形误差或超差。

A.对中对刀不准

B.分度头精度低

C.铣刀磨钝

D.切深对刀不准