✔ 最佳答案
首先多嘴告訴你001的回答係錯的-英文沒有was been xing這種文法的
你的答案基本是對的「現在完成進行式」,但通常這種時態表達時都會加上一些時空指標,因為這時態結構本身已表示由某時間開始至今仍在做,所以如果能夠指示埋那某時是何時便更理想和完整了。
Sam has been repairing these cars since 9:00am.
或更詳細地交代
Sam has been repairing these cars since 9:00am after Mary took these 10 cars to Sam at 8:30am.