—Shallwegooutforawalk?     —Sorry,Ican’t.I

問題詳情：

—Shall we go out for a walk?

      —Sorry, I can’t. I _______ my homework.

   A. do                     B. did                       C. am doing                D. was doing

【回答】

C

知識點：動詞時態

題型：選擇題