"I do not have a cat."

Translation: Eu não tenho um gato.

[Seleuco]

Colloquialy speaking, it would be way more natural to say "eu nao tenho gato". Duo should accept this as a valid option.

[Doaso169]

I need with when to use tenho and tem. When do I know when to use which?

[mgaristova]

Eu tenho = I have
Ele/ela/você tem = he/she has/you have

[Adrram647]

I have no idea when to use the correct grammatical word