Past Simple: To Be

Pay attention to the forms of to be in past simple:
I was
you were
She was
He was
It was
We were
They were

Examples of past simple positive sentences with to be:
I was on a business trip last week.
They were interested in the presentation.

In order to create negative sentences with to be we add ‘n’t’ or ‘not’.
I wasn’t late for the meeting this morning.
I was not late for the meeting this morning.
She wasn’t with her friends last Saturday.
She was not with her friends last Saturday.
We weren’t at the office yesterday.
We were not at the office yesterday.

To create questions with to be in past simple we use inversion:
Were you on a business trip last month?
Was she at the office yesterday?
Where were you last night?
How was the meeting?