问题描述：
Why?Tom,your skirt is so dirty!
Mum,I ___ my storeroom downstairs.
A cleaned B have cleaned C was cleaning D have been cleaning
为什么选D不选B呢?
Mum,I ___ my storeroom downstairs.
A cleaned B have cleaned C was cleaning D have been cleaning
为什么选D不选B呢?
问题解答：
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