虚拟语气的翻译：我本来打算做什么，（但没有做）. would have done的两种用法 见内：

Would Have

'Would have' is used in the third type of conditionals to express a hypothetical or unrealized action in the past or to express regret or disappointment about a past event. The structure of such sentences is as follows:

• [Clause 1](If + past perfect) + [Clause 2](would + have + past participle)

Check out the following examples:

If I had known you were sick, I would have visited you in the hospital.  

If she had his number, none of this would have happened.  

'Would have' can also be used to express a desire that was not fulfilled in the past. For example:

I would have liked to attend the conference, but I had other commitments.  

I would have preferred to take the earlier flight, but it was fully booked. 

 

https://langeek.co/en/grammar/course/684/would-vs-would-have#