it might/could be the case that
Certain
there is every chance that
Fairly certain
Most probably
I am not really sure if
I think it is debatable whether
No one can predict whether
There is a strong possibility that
It is highly likely
It's impossible to say whether/if
Cannot definitely say
I can say without a doubt/most definitely that
Certain
Fairly certain
quite possible
Fairly certain
fairly certain
Uncertain
Fairly certain
Uncertain
There is no question in my mind that
Certain
I am quite/totally/utterly convinced that
Fairly certain
Uncertain
Uncertain
Uncertain