Помогите пожалуйста решить 2 и 3 упражнение. Заранее благодарен.

1Were you a student last year?Yes,I was
2.Were your friends at your house last week?Yes,they are
3.Was your teacher at work last Saturday?Yes, he/she was
4.Were you and your classnates at the library last night?No,we weren't