公文的语言要求主要是:准确,简约,生动,得体。
参考答案:错
—Did you meet the professor at the airport?
—No,he ____ by the time I ____ there.
A.had left;got
B.has left;reached
C.was leaving;got
D.left;had got
如果()变化,并不改变工步的划分。
A.加工表面
B.切削刀具
C.切削用量
D.走刀次数