刃磨成形车刀、铲齿铣刀或滚刀前面时，必须严格控制前角的大小和原有几何参数，才能保证切削刃形状不产生畸变。( )
参考答案：对
Woman: What’s the difference between a lesson and a lectureMan: Well, they are both ways of imparting knowledge, but the main difference is that you participate in a lesson whereas you just Iisten to a lecture. A lecture is generally given to a much larger group.Question: What does the man mean
A．A lesson requires students’ active involvement.
B．Students usually take an active part in a lecture.
C．More knowledge is covered in a lecture.
D．There is a larger group of people interested in lessons.
隔音门主要有那几种？
