基本形式：（1）would + be + 动词的过去分词（2）was / were +going to be + 动词的过去分词。eg. I knew the work would be finished by 5:00 PM。
我们通过例句来感受下被动态： （1） I knew John would finish the work by 5:00 PM. (Active) 我知道约翰会在5点前结束工作。（主动） I knew the work would be finished by 5:00 PM. (Passive) 我知道工作会结束于5点之前。（被动）
（2） I thought Sally was going to make a beautiful dinner. (Active) 我想萨里会去做一顿丰盛的晚餐。（主动） I thought a beautiful dinner was going to be made by Sally. (Passive) 我想一顿丰盛的晚餐会出自萨里之手。（被动）
（3） I believed that Jack was going to write a letter to Tom. (Active) 我相信杰克会给汤姆写信的。（主动） I believed that a letter was going to be written to Tom by Jack. (Passive) 我相信有封信会写自杰克之手并被交给汤姆。（被动）
（4） I knew that my sister would buy a house. (Active) 我知道我姐姐要买房了。（主动） I knew that a house would be bought by my sister. (Passive) 我知道有一所房子要被我姐姐买下了。（被动）