It's possible.
B1It could happen.
It's unlikely.
B1It probably won't happen.
I doubt it.
B1I think it's improbable.
I'm not so sure.
B1I'm hesitant.
I'm not convinced.
B1I'm not persuaded.
Perhaps.
B1Maybe.
Maybe.
B1Possibly.
It's a possibility.
B1It could happen.
I think so.
B1I believe it's true.
I don't think so.
B1I believe it's not true.
I believe so.
B1I have reason to think it's true.
I reckon.
B1I think.
In all probability.
B1Very likely.
Without a doubt.
B1Certainly.
For sure.
B1Definitely.
It's a long shot.
B1It's unlikely to succeed.
Chances are...
B1It's likely...
I would say so.
B1I think so.
I'd guess so.
B1I think so, but I'm not certain.
It's a safe bet.
B1It's highly probable.
I'm pretty sure.
B1I'm almost certain.
There's no doubt about it.
B2It's certain; there's no question.
It's a foregone conclusion.
B2The outcome is certain and predictable.
It goes without saying.
B2It's obvious and needs no explanation.