Ответ:

Mike was a student

Mike wasn't student

Was Mike a student

you were a good friend

you weren't a good friend

were you a good friend

1) (+)Mike was a student

   (-)Mike was not a student

   (?)Was Mike a student?

2) (+) You were a good friend

    (-) You were not a good friend

    (?) Were you a good friend?

PS: можно поставить показатели времени такие как yesterday(вчера), the day before yesterday(позавчера), three\two years ago(два или три года назад), last week\month\year(прошлой\прошлого недели, месяца, года)

+ утвердительное

- отрицательное

? вопросительное