第595天 被动语态 3

• 过去完成时的被动语态构成：had + been + done
  He said that some new factories had been built in the city.
  The classroom hadn't been cleaned before the teacher came.
  The tickets had been sold out before I came to the cinema.

• 将来完成时的被动语态构成：shall/will + have been done
  They will have been married for 10 years by next year.
  The project will have been completed before May.

• 含有情态动词的被动语态构成：情态动词+ be + done
  Your mistakes should be corrected right now.
  Young trees must be watered often.
  Your homework must be handed in tomorrow.

秘诀：在 be done结构中，done(及物动词的过去分词) 永远不变，不同时态 只需变化be动词为相应的时态形式即可。