Adverb of certainty
An adverb of certainty basically gives information about how sure we are of something. It normally goes in mid-position, i.e. either after auxiliary verbs and be or before other verbs. However, perhaps and maybe typically go at the beginning of a clause.
Typical adverbs of certainty
- certainly, definitely, likely*, obviously, probably
* As an adverb, in British English, likely needs to be accompanied by a preceding intensifying adverb (it will very likely rain or it will most likely rain), but not in colloquial American English.