—Must I finish my homework?

—No, you _____. You may do it tomorrow.[ ]

A. needn't

B. can't

C. mustn't

D. couldn't

在机械加工中，通常采用______的方法来进行加工螺纹。

A．车削螺纹

B．滚压螺纹

C．搓螺纹