Dialog bahasa inggris tentang asking for giving certainty

sehun: jungkook what is certainy i never know that,do you know
jungkook: mmmmm,i'm not sure but we can search at google oke let me see
sehun:faster okayy
jungkook: oohh certainy is present perfect and past simple i think my sister talk abou that yesterday
bell
sehun:it's already bell bye
jungkook: bye..