Adverbs of certainty let us describe how sure or certain we are about something. Here are the most common adverbs of certainty.

• definitely – 100% sure
• probably – pretty sure; 70-90% sure
• maybe – 50% sure
• probably not – 70-90% sure of something not happening or being true
• definitely not – 100% sure of something not happening or being true

Here are some other adverbs of certainty that we must know.

• surely
• certainly
• undoubtedly
• clearly

We usually use these with the future tense and the present tense.

• I will definitely good.
• The movie will undoubtedly be sold out.

But it is also possible to use them with the past tense to guess or make assumptions about the past.

• She probably went home.
• He definitely stole the diamonds.

Now, let's see where we put these adverbs. It can be different depending on the verb tense and sentence.

Here is where we put these adverbs in the present tense and past tense.

Subject + adverb + verb…
Subject + be verb + adverb + (not)…

• She definitely works here.
• He probably likes sports.
• She probably doesn't like me.
• I definitely need to shower.
• He definitely went home.
• They probably left early.
• They are definitely brothers.
• It is probably bad.
• The girl is probably not a good student.
• It was probably canceled.

If we are making a negative sentence, we do not use contractions. Put "not" after the adverb.

• The movie isn't probably good.
• The movie is probably not good.

Here is where we put these adverbs in the future tense with "will".

Subject + will + adverb + (not) verb…
Subject + will + adverb + (not) be…

• I will probably go.
• I will probably not go.
• It will definitelyrain tomorrow.
• She will probably not come.
• He will definitely not come.
• It will definitely not be good.
• He will probably not be hungry.
• He will certainly be upset.

If we are making a negative sentence, do not use the contraction "won't" before the adverb. Put "not" after the adverb.

• It won't definitely rain.
• It will definitely not rain.

Many English speakers use the contraction "won't" after the adverb.

• It definitely won't rain.
• She probably won't be at the party.

Adverbs are used freely by most native English speakers. So, do not be surprised if you hear English speakers using the adverbs before "will".

• He definitely will not come.
• She probably will quit.
• She probably won't be angry.
• They surely won't be happy.

If we use the present continuous or "going to + verb" to talk about the future, then we put the adverb after the "be verb". Just like the present or past tense.

• She is probably going to come.
• They are definitely not going to be happy.
• It is definitely not going to rain tomorrow.

Some adverbs of certainty go at the beginning of a sentence.

Put "maybe" at the beginning of a sentence. We can use "maybe" with any verb tense.

• Maybe, I will go.
• Maybe,she went home.
• Maybe, she doesn't like chocolate.
• Maybe,he has never been here before.

Here are some other adverbs of certainty that often go at the beginning of a sentence.

• Surely, you are joking.
• Certainly, he will not do that.
• Probably, he went home.
• Undoubtedly, he is the best player of all time.

Practice speaking English and improve your English grammar by finishing the sentences below and then practice making your own sentences. It is the best way to learn English and improve your English fluency fast! Also, do not forget to try using it in real life.

I will definitely _______________ tomorrow.
She will probably _______________ later today.
He will probably not _______________ next week.
My family will probably _______________ during the next holiday.
My best is probably _______________ right now.
They are probably at _______________ right now.
Maybe, I will _______________ later.
Maybe, she will _______________ later.
(Friend's Name) is undoubtedly my best friend.
Surely, _______________ tomorrow.
I am certainly the best _______________ in my family.