当数控机床失去对机床参考点的记忆时，必须进行返回参考点的操作。（）
参考答案：错
She said she _______ the new coat for only a week.[ ]
A. has bought
B. had bought
C. has had
D. had had
Mr. Black ______ Shanghai in a few days. Do you know when the earliest plane ______
on Sunday? [ ]
A. is leaving, takes off
B. leaves, takes off
C. is leaving, is taking off
D. leaves, is taking off
