Asking for Certainty: Are you sure? Are you sure about it? Are you certain about it? Do you think it is true? Do you think so? How sure are you? Expressing Certainty: Yes, I am certain. I’m a hundred percent certain … I’m absolutely sure. I have no doubt about it. I’m sure about it. I don’t think there can be any doubt about …. Of course. I’m positive. I’m quite sure about it. I’m no doubt about it. I’m absolutely certain that… Expressing Uncertainty: I’m not sure about it. I doubt it. I’m not really sure about… I don’t know for sure… It’s very unlikely. I have my own doubts. I don’t think so. I don’t believe this is true. There’s some doubt in my mind that … I’m not a hundred percent sure. I don’t know yet.
