This is very simple. You can’t say could of.

He could have driven more carefully.
The same for would have and should have.
• I should have played for Liverpool. RIGHT
• He was here yesterday so, he would of met my new girlfriend. WRONG
Remember: No could of.
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Remember: No could of.
I could have done more training before running the marathon.
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Vocabulary Video Lesson: Etiquette 2
This vocabulary lesson will help you define point, shake hands, greet, stare, yawn, slurp, burp and interrupt. (8:00)If you only have two minutes then do this lesson.
Have something done (2:00)