车孔时，表面粗糙度值较大的原因可能是（）。
A.车刀磨损
B.刀杆振动
C.切削速度不当
D.产生积屑瘤
参考答案：A, B, C, D
Please remind me he said he was going. I may be in time to see him off. [ ]
A. where
B. when
C. how
D. what
简述合理劳动关系的标志。
