The structure of the Past Simple is the same as it is in the Present Simple! The only difference is that we must substitute the Present form of the verbs for the Past forms.
Remember the mantra. Subject, verb, complement.
The verb “to be” works differently from normal verbs, just like it does in Present Simple.
Here is the structure for the verb ‘to be’ in Past Simple. Compare this with how we make affirmative (+), negative (-) and interrogative (?) sentences in Present Simple. What is the same? What is different?
The structure is exactly the same. The difference is that we use ‘was’ and ‘were’ instead of ‘am’, ‘is’ and ‘are’. Here is what it looks like:
I was at the store.
you were at the store.
He/she/it was at the store.
We were at the store.
They were at the store.
Other verbs, like “have”, “like” and “run”, follow the same structure as the Present Simple too. But in the Past, instead of “do” or “does”, to form negatives and questions.
You can see the pattern here:
To look at the same idea a different way, think about it like this:
SUBJECT VERB COMPLIMENT
Frank discovered a cave.
SUBJECT DID NOT VERB COMPLIMENT
Frank didn’t discover a cave.
DID SUBJECT VERB COMPLIMENT
Did Frank discover a cave?
WHEN DO WE USE THE PAST SIMPLE?
We use the Past Simple to talk about:
1.) completed actions in the past.
For example: Frank went up to the mountains yesterday at 2PM.
2.) single events, habits and moods.
For example: Frank loved Nature when he was a child. He camped every weekend.