—Icalledyouat4:00yesterdayafternoon,butnooneanswered.  ...

問題詳情：

— 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

【回答】

D

知識點：動詞時態

題型：選擇題