Was\Were - Wasn't\Weren't

I was in the park yesterday.

He was in the park yesterday.

We were in the park yesterday.

I wasn't in the park yesterday.

He wasn't in the park yesterday.

We weren't in the park yesterday.

You weren't in the park yesterday.

You were in the park yesterday.

Was/Were (Wasn't/Weren't) are the past tense forms of the "be" verb (is, am, are).