You could have called me to let me know you'd be late.

You could have taken an umbrella, it's raining outside.

You could have asked for help if you were struggling.

You could have studied harder to get a better grade.

You could have chosen a different restaurant, this one is always crowded.

You could have saved money by buying the product on sale.

You could have told me you weren't interested instead of leading me on.

You could have fixed the leak before it caused more damage.

You could have avoided the accident if you had been more careful.

You could have done a better job if you had more time to prepare.