过去将来时的被动语态的概念：

过去将来一般时的被动语态的主语是第一人称时用should be加及物动词的过去分词构成；主语是第二、三人称时用would be加及物动词的过去分词构成。
例如：He said that something would be needed to finish the task. 他说要完成这项任务，需要某种条件。 
          

过去将来时的被动语态的用法：

过去将来时的被动语态常出现在英语间接引语中，其形式为：
(1)would/should+be+动词的过去分词
(2)was/were+going to be+动词的过去分词.
如：He said the project would be finished by the time we reached there.
        She said that some new factories would be built soon in our city.  
        He thought that your watch was going to be mended after an hour.
        He said that something would be needed to finish the task. 他说要完成这项任务，需要某种条件。
        It was said that they would be selected by lottery. 据说他们将抽签选出。