PAST TENSE

• IF IN THE PRESENT SIMPLE, THE VERB TO BE HAS THREE FORMS (AM, IS, ARE), IN THE SIMPLE PAST, IT HAS TWO: WAS AND WERE.
• WAS CORRESPONDS TO THE FIRST PERSON SINGULAR (I) AND THE THIRD PERSON SINGULAR (HE, SHE, IT); WERE USED FOR OTHER PEOPLE (YOU, WE, THEY).

• EXAMPLE :

I WAS AT WORK.
YOU WERE QUITE ILL.
WE WERE IN SCOTLAND LAST WEEK

• 
  AS CAN BE SEEN, IN THE SIMPLE PAST TENSE, NO CONTRACTION IS FORMED BETWEEN THE PRONOUN AND THE VERB TO BE. BOTH WAS AND WERE APPEAR ALONE.
• EXAMPLE:

YOU WERE IN ENGLISH CLASS.
IT WAS GOOD.
THEY WERE AT HOME.

HOWEVER, WHEN THE PHRASE IS NEGATIVE, THE CONTRACTION IS MADE BETWEEN WAS AND NOT AND WERE AND NOT:

I WAS NOT	I WASN’T
YOU WERE NOT	YOU WEREN’T
HE WAS NOT	HE WASN’T
SHE WAS NOT	SHE WASN’T
IT WAS NOT	IT WASN’T
WE WERE NOT	WE WEREN’T
YOU WERE NOT	YOU WEREN’T
THEY WERE NOT	THEY WEREN’T

EXAMPLE:

HE WASN’T A MEMBER OF THE CLUB.
IT WASN’T COLD.
THEY WEREN’T LATE.

AS ALWAYS HAPPENS IN ENGLISH, YOU HAVE TO CHANGE THE ORDER OF THE PHRASE TO ASK THE QUESTION. WITH THE ANSWER WE CAN MAKE A "LINGUISTIC SHORTCUT" WHEN ANSWERING WITH THE AUXILIARY VERB, THAT IS, WITH WAS OR WERE:

questions	short  questions
WAS I AT HOME?	YES, I WAS / NO, I WASN’T
WERE YOU AT WORK?	YES, YOU WERE / NO, YOU WEREN’T
WAS HE CANADIAN?	YES, HE WAS / NO, HE WASN’T
WAS SHE A DOCTOR?	YES, SHE WAS / NO, SHE WASN’T
WAS IT SLEEPING?	YES, IT WAS / NO, IT WASN’T
WERE WE THERE?	YES, WE WERE / NO, WE WEREN’T
WERE YOU READY?	YES, YOU WERE / NO, YOU WEREN’T
WERE THEY STUDYING?	YES, THEY WERE / NO, THEY WEREN’T

SOME VIDEOS TO LEARN MORE ABOUT THE PAST TENSE

https://learnenglish.britishcouncil.org/en/english-grammar/past-tense

https://www.ef.com/english-resources/english-grammar/simple-past-tense/

https://www.grammarly.com/blog/simple-past/

EXERCISES REINFORCE WHAT LEARNED                                                            https://www.curso-ingles.com/practicar/ejercicios/past-simple
https://english.lingolia.com/es/gramatica/tiempos-comparacion/past-tenses/ejercicios
https://english.lingolia.com/es/gramatica/tiempos-verbales/simple-past/ejercicios