New or knew:
The words knew and new are homophones which means they sound alike but mean different things.
New is an adjective that means unused.
Knew is the past tense form of the verb know, which means to understand or to be aware of.
If you are having trouble using these words correctly, remember that knew is a verb and has to do with knowledge. Since both of these words start with the same two letters, you can link them together in your mind.