Adverbs of certainty express how certain or sure we feel about an action or event.
Common examples are: certainly, definitely, probably, undoubtedly, clearly, obviously etc.
- He is undoubtedly a great leader.
- There is clearly something wrong.
- She is definitely taller than you.
- He is undoubtedly a great leader. (is/am/are/was/were + adverb)
- She will probably come. (auxiliary verb + adverb + main verb)
- It will certainly rain this evening. (auxiliary verb + adverb + main verb)
- I certainly feel better today. (adverb + main verb)
- You have definitely been working too hard. (first auxiliary + adverb + second auxiliary + other verb)
Perhaps and maybe are exceptions to this rule. They usually go at the beginning of a clause.
- Perhaps she will come.
- Maybe you are right.