Pasts

Past Simple : 

VERB+ed o irregular verbs 

Example : 
You called Debbie.
Did you call Debbie

Use the Simple Past to express the idea that an action started and finished at a specific time in the past. Sometimes, the speaker may not actually mention the specific time, but they do have one specific time in mind.

Examples:

• I saw a movie yesterday.
• I didn't see a play yesterday.

Past Continous :

was/were + present participle

Exemple : 
You were studying when she called.
Were you studying when she called ?


Use the Past Continuous to indicate that a longer action in the past was interrupted. The interruption is usually a shorter action in the Simple Past. Remember this can be a real interruption or just an interruption in time.

When the phone rang , she was writing a letter.