Expressions of Certainty and Uncertainty

I am certain.

I am confident.

Without a doubt.

Completely; without question.

Certainly.

I believe it's likely.

I have reason to think it's true.

I suppose it's possible.

Likely.

Possibly.

Possibly.

I am uncertain.

I lack knowledge about this.

I think it's unlikely.

It's improbable.

I'm not completely sure.

It could happen.

I think so, although I'm not completely sure.

I'm not persuaded.

The situation is somewhat unclear.

I have no doubt.

It's certain.

I'm confident.

It's very probable.