Learn how to say I Do Not Know correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word know:
verb (past knew /njuː/; past participle known /nəʊn/)
1 [with clause] be aware of through observation, inquiry, or information:
most people know that CFCs can damage the ozone layer
I know what I’m doing
[with object] have knowledge or information concerning:
I would write to him if I knew his address
I know of one local who shot himself
be absolutely certain or sure about something:
I just knew it was something I wanted to do
I knew it!
2 [with object] have developed a relationship with (someone) through meeting and spending time with them; be familiar or friendly with:
he knew and respected Laura
have a good command of (a subject or language).
recognize (someone or something):
Isabel couldn’t hear the words clearly but she knew the voice
be familiar or acquainted with (something):
a little restaurant she knew near Leicester Square
have personal experience of (an emotion or situation):
a man who had known better times
(usually be known as) regard or perceive as having a specified characteristic:
the loch is known as a dangerous area for swimming
(usually be known as) give (someone or something) a particular name or title:
the doctor was universally known as ‘Hubert’
(know someone/thing from) be able to distinguish one person or thing from (another):
you are convinced you know your own baby from any other in the world
3 [with object] archaic have sexual intercourse with (someone).
[a Hebraism which has passed into modern languages; compare with German erkennen, French connaître]