问题补充:
----I called you at 4:00 yesterday afternoon ,but nobody answered.
----Sorry,Iwith my friends at that time.
A. swim
B. swam
C. will swim
D. was swimming
答案:
A. swim
B. swam
C. will swim
(答案→)D. was swimming
解析:句意:昨天下午我给你打电话了,但是没人接。很抱歉,那时我正在和朋友游泳。at that time是过去进行时的标志词,结合句意,故选D.