???Which of the following sentences is grammatically correct? =We wasn't at school last week. =We aren't at school last week. =We weren't at school last week. =We don't at school last week.

Для определения грамматически правильного предложения, нужно проверить согласование подлежащего и сказуемого.

Правильное предложение: We weren't at school last week.

Ответ: =We weren't at school last week.