• Perfect Modals: Would Have

• 
• Use the perfect modal form of would to show certainty* about actions/events in the past.
  

  
  

  subject + would + have + past participle
  

  
  

  -John would have hated the movie we saw last night. He doesn't like horrors.

  (It is a fact that John hates horror movies. This person knows John wouldn't like the movie they saw.)

  
  

  You often see would have paired with should have.

  -Amanda should have visited  France. She would have loved it!

  (This person is certain that Amanda would like France.)

• I would have helped you study for the final exam. You didn't ask! Sue would have taken  Professor Smith's class, but she didn't have time in her schedule. You should have studied education. You would have been a great teacher!

• *Certainty: to know something for a fact, having no doubt that something happened/will happen

 Source : Alison