问题
选择题
Mrs Black isn't in and I'll have to ring _____. I would appreciate 
it if you ring _____ after 6 o'clock.[ ]
A. off; back
B. up; off
C. out; up
D. back; off
答案
答案：A
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Mrs Black isn't in and I'll have to ring _____. I would appreciate it if you ring _____ after 6 o'clock.[ ]
A. off; back
B. up; off
C. out; up
D. back; off
答案：A