know one is alive Idiom
know one is alive|alive|know
v. phr. Not to notice a person.

Used with negative or limiting words and in questions.
She was a good-looking girl but she didn't know I was alive. Compare: GIVE A HANG.
know one is alive|alive|know
v. phr. Not to apprehension a person.

Used with abrogating or attached words and in questions.
She was a attractive babe but she didn't apperceive I was alive. Compare: GIVE A HANG. Dictionary