ExercisesContentsDownloadsUNIT 13: PAST SIMPLE, PAST CONTINUOUS, PAST PERFECTQuestion 1 / 10请完成全部题目,最后查看答案与解析GRAMMAR · B1 Exercise 1 · Exercise 1Choose the correct answer.I was very late. When I arrived, the conference _____.Awas already startingBstartedChad already started保存并进入下一题 →