After school we went to the reading-room to do some reading, only to be told that it .A.

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A. was decorated
B. had decorated
C. had been decorating
(答案→)D. was being decorated
解析：考查时态：句意：放学后，我们去阅览室看书，结果被告知阅览室正在装修。所以这个动作是过去正在进行，而且the reading-room和 decorate是被动关系，用过去进行时的被动。选D。