問題詳情：
—Mum, Tom is always working late into night. I don't know what he is busy doing.:狀_元_源Z_—Oh ,he _____for his new project.
A. has prepared B. had prepared C. has been preparing D. was preparing
【回答】
C
知識點：現在完成進行時及其被動式
題型：選擇題
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