21. A:How did the accident(事故)happen?B:I don’t know. ______ the car hit(撞)the train, I ______.(A) Wh
問題詳情
21. A:How did the accident(事故)happen? B:I don’t know. ______ the car hit(撞)the train, I ______. (A) When; am sleeping (B) When; was sleeping (C) Before; didn’t sleep (D) After; wasn’t sleeping