对于轴类零件的圆柱面检测方便、容易实现,故应优先考虑。
A. 圆度
B. 跳动
C. 圆柱度
D. 同轴度
It ______ five years since he has left for Beijing.
A. was
B. have been
C. is
D. is going to be
We can’t find him anywhere. Perhaps he ______ home.
A. is going
B. went
C. has gone
D. had gone
Could you tell where the railway station ______?
A. was
B. is
C. will be
D. would be