何谓主截面?在主截面内测量的角度有哪些?
参考答案:
通过主切削刃上的一点,并与主切削刃在基面上的投影相垂直的平面称为主截面。在主截面内测量的角度是:前角、后角和楔角。
W: Your spoken English is very good. I like it very much.
M: Thank you! Yon see, I’ve ever stayed in England for five years and during that time my oral English was improved a lot.
How long did the man stay in England ()
A. Two years.
B. Three years.
C. Four years.
D. Five years.
《特种设备安全监察条例》调整了特种设备()环节。
A.制造
B.销售
C.安装
D.维修