初中英語時態(tài)知識點：過去進行的結構

　　過去進行時的結構及句型變化

　　過去進行時由was / were + 現(xiàn)在分詞構成。如：

　　I was doing my lessons then. 那時，我在做功課。

　　We were cleaning the house. 我們在打掃房子。

　　過去將來時態(tài)的肯定句、否定句和疑問句形式：

　　肯定句例句：I was walking down the street when a UFO landed.

　　否定句例句：I wasnt walking down the street when a UFO landed.

　　一般疑問句例句：Were you walking down the street when a UFO landed?

　　特殊疑問句例句：What were you doing when a UFO landed?