He had to be reminded two or three times he could avoid making the same mistake.A. befor

He had to be reminded two or three times he could avoid making the same mistake.
A. before
B. until
C. when
D. after

(答案→)A. before B. until C. when D. after解析：连词辨析。A.在……之前 B. 直到…… C. 当……时 D. 在……之后。句意：在他可以避免犯同样的错误之前，不得不提醒他三到两次。选A。

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