I cleaned my classroom _ Awith there hours B.three hours ago C.in there hours D.there hours before
问题描述：
I cleaned my classroom _ Awith there hours B.three hours ago C.in there hours D.there hours before
答
B.three hours ago
A选项不能判定时态,而题中是过去时
C选项语法错误
D选项中before一般不被用于具体时间之后,大部分是作为连词用在句首或句中
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