real life pre-inter u6 obligation and permission in the past

real life pre-inter u6 obligation and permission in the past

how to make permission in the past.

• is allowed : was allowed

• isn't allowed : wasn't allowed

• are allowed : were allowed

• aren't allowed : weren't allowed

• can : could

• can't : couldn't

how to make obligation in the past.

• have to : had to

• don't have to : didn't have to