卧式升降台铣床的工作台面应平行于主轴轴心线,其误差方向只允许工作台台面远离主轴侧()。
A.向下偏
B.向上偏
C.与主轴轴线平行
D.随间方向
参考答案:B
18. ----- Has Mary finished writing her article ?
----- No, and it _____ before class was over.
A.should be finished
B.should finish
C.should have finished
D.ought to have been finished
盛装双氧水的化学试剂瓶外签腐蚀后,未及时贴好标识会造成什么后果?