—— Why? Tom your shirt is so dirty! —— Mum I ＿＿＿＿＿ my storeroom downstairs。A. cleanedB.

问题补充：

—— Why? Tom, your shirt is so dirty!

—— Mum, I ＿＿＿＿＿ my storeroom downstairs。

A. cleaned

B. have worked

C. was cleaning

D. have been cleaning

答案：

A. cleaned

B. have worked

C. was cleaning

(答案→)D. have been cleaning

解析：现在完成进行时表示从过去某时到现在一直在进行的动作。