—Ididn’tseeyouatthebeginningofthepartylastnight.—I　　　on...

問題詳情：

—I didn’t see you at the beginning of the party last night.

—I 　　　 on my biology report at that time.

ed          working   working

【回答】

C　

知識點：動詞時態

題型：選擇題