1 Rewrite the sentences in the past simple. 0 It isn't fun.
It wasn't fun.
1 We aren't at school.
2 It's very cold.
3 I'm at a party.
4 She isn't at the park.
5 Is he at home?
6 You're very happy.​

1. We weren't at school.

2. It was very cold.

3. I were at a party.

4. She wasn't at the park.

5. Was he at home?

6. You were very happy.

Past Simple: глагол в начальной форме становится глаголом в времени. Для неправильных глаголов (исключений) нужно учить две формы времени.  

Например: come --> came (не comed!). Эти формы лучше знать наизусть.

Для правильных: глагол + окончание ed, например:

время глагола "работать".

Здесь же, изменяется форма глагола be ("быть") для второго числа, единственного и множественного чисел.

Ед.ч. : is / isn't (is not),  am;

Мн.ч.: are / aren't (are not).

В времени:

is --> was

isn't --> wasn't

are --> were

aren't --> weren't

am --> were и was