Ответ:
My friend wasn't at the cinema last night.
The children wasn't at the skating-rink last Sunday.
My aunt wasn't at the library yesterday.
I wasn't at school last summer.
My parents were at the office yesterday.
My brother wasn't at the institute last night.
Объяснение:
wasn't это единственное число
were множественное поставьте лайк если не жалко