certain

sure

Knowing that something is true and having no doubt about it.

know

To have information about something, or to be familiar with a person.

clear

Easy to see, hear, or understand; with nothing in the way.

think

To use your mind to form ideas, opinions, or beliefs about something.

particular

One special thing and not any other; used to point at the exact one you mean.

surely

You say this when you feel certain about something and expect other people to agree.

definitely

For sure, with no doubt at all.