You may feel that way, but I don't know. Why do you think so? You may be right. You probably have a good reason to believe so. I'm not so sure you're right. Could be; you know him better than I do.
Thank you Philip, but those phrases do not express exactly what I want to say.I mean " That's just your opinion. I have no idea"
For example, when the manager asks us to do some tasks Mr A , my colleage, says" these tasks are easy. We can finish them in one day" , and I say" That's your own opinion" (I mean What Mr A says is just his opionion.For me, It's not sure that these tasks are ea
What the speaker of that sentence actually means is something like this: "I'm pretty sure you're wrong; the reality (of whatever is being discussed) is different from what you think it is".