There isn’t anybody in the room.
There isn’t anyone in the room.
There is nobody in the room.
There is no one in the room.
A: Who is in the room?
B: Nobody. / No one.
There isn’t anything in the bag.
There is nothing in the bag.
A: What’s in the bag?
B: Nothing
not+anybody/anyone
I don’t know anybody (or anyone) here.
I’m lonely. I have nobody to talk to. (= I don’t have anybody)
The house is empty. There is no one in it. (= There isn’t anyone in it.)
not+anything
I can’t remember anything.
She said nothing (= She didn’t say anything)
There’s nothing to eat (= There isn’t anything to eat)
The house is empty. Nobody lives there.
-Who did you speak to?
-No one.
Nothing happened.
-What did you say?
-Nothing.
He doesn’t know anything (not He doesn’t know nothing)
Don’t tell anybody. (not Don’t tell nobody)
There is nothing to do in this town. (not There isn’t nothing)