It doesn't even sound wrong. It is something people use. Just not as often.
"Is this the thing you're looking for?"
"That is not it."
That isn't it That is not it it
Isn't = is not, where are you getting the second it from?
It doesn't even sound wrong. It is something people use. Just not as often.
"Is this the thing you're looking for?"
"That is not it."
That isn't it That is not it it
That isn't it That is not it it
Isn't = is not, where are you getting the second it from?