could have done it
I could have done it.
Probablemente, podría haberlo hecho sin tu ayuda.
I probably could have done it without your help.
Tom podría haberlo hecho.
Tom could have done it.
He could have done it.
Cualquier idiota podría haberlo hecho.
Any idiot could have done it.
— Who Am I: Ningún sistema es seguro (2014)
Podría haberlo hecho mejor si hubiera tenido tiempo.
I could have done better if I had had more time.