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? |