Please help me with placing of "probably" in negative sentences.
My workbook says that 'probably' comes before helping verb. For example,
Anna probably won't be in class tomorrow
Anna probably isn't going to be in class tomorrow.
So I did some exercises and the answers for them doesn't match with this rule. The same workbook also suggest sentences like this:
They are probably going to invite.
They are probably NOT going to invite
I'm probably going.
I'm probably NOT going.
So what's the rule? Should we place it before or after 'to be' and auxiliary words?