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题目内容
（河南财经政法大学-金融学-大学英语4）
__________ how to operate a switchboard, I had to ask the office supervisor to show me the correct procedures.
A.Not known
B.Not to know
C.Not knowing
D.Having not known
A.Not known
B.Not to know
C.Not knowing
D.Having not known
参考答案