—I called you at 4:00 yesterday afternoon, but no one answered.
—Sorry, I ______ with my friends at that time.
- A.swim
- B.swam
- C.will swim
- D.was swimming
答案
正确答案:D
知识点:过去进行时

首句说:我昨天下午4点钟给你打电话,但是没人接。下句显然是要告诉对方当时正在做什么,故用过去进行时。

注意也可根据答语中后面的标志词“at that time”(在那时)进行判断。
