型态
在第三类条件句中，会用到条件式完成进行时。
| if 子句（条件/情况） | 主要子句（结果） |
|---|---|
| if 过去完成时 | 条件式完成进行时 |
| if this thing had happened | that thing would have been happening. |
作用
完成进行时可以用在第三类条件句，论及 if 子句中的动作未达成的后果，并将这样的后果以未完成或持续进行的动作来表达。
举例
- if the weather had been better（但没有）, i'd have been sitting in the garden when he arrived（但我没有）.
- if she hadn't got a job in london（但她有）, she would have been working in paris（但她没有）.
- if i had had a ball i would have been playing football.
- if i had known it was dangerous i wouldn't have been climbing that cliff.
条件式完成进行时
任何动作的条件式完成进行时都是由四个要素组成：
would have been 现在分词
现在分词的构成是取动词的原型，并在字尾加上 ing。
| 主词 | would | have | been | 现在分词 |
|---|---|---|---|---|
| he | would | have | been | staying |
| they | would | have | been | going |
条件式完成进行时，以 to work 为例：
| 肯定句 | 否定句 | 疑问句 | 否定疑问句 |
|---|---|---|---|
| i would have been living | i wouldn't have been living | would i have been living? | wouldn't i have been living? |
| you would have been living | you wouldn't have been living | would you have been living? | wouldn't you have been living? |
| he would have been living | he wouldn't have been living | would he have been living? | wouldn't he have been living? |
| she would have been living | she wouldn't have been living | would she have been living? | wouldn't she have been living? |
| we would have been living | we wouldn't have been living | would we have been living? | wouldn't we have been living? |
| they would have been living | they wouldn't have been living | would they have been living? | wouldn't they have been living? |