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Mary quickly closed the door of her room her father could reach it to keep him out.
A. before
B. when
C. as
D. while
网友回答
(答案→)A. before
B. when
C. as
D. while
解析：连词辨析。Before在……之前； when 当……时；as 随着，由于；while然而，当……时。句意：，为了把他挡在外面，在他能够到它之前玛丽快速的把她房间的门关上了。故选A。