What Are Modal Verbs of Deduction?

modal verbs of deduction. This is when you look at something and try to guess what it is. It couldn't have been you, my love. I mentioned that earlier. So couldn't is a modal verb here. The thing about modal verbs is that when students of English approach the learning of modal verbs, they want to get each one right. They want to understand what that individual modal verb means and how it's used every time.