Theyhavebeen

問題詳情：

They have been ________ over chairs, ________ into doors, and ________ down on stage for years.

  A. tripped, walking, fell          B. tripped, walked, fell

  C. tripping, walking, falling       D. tripping, walking, fell

【回答】

C

知識點：非謂語動詞

題型：選擇題