Cấu trúc của thì quá khứ đơn (đối với tobe)
Khẳng định: S + was / were + O
Ví dụ: I was a student two years ago.
Phủ định: S + was / were + not + O
Ví dụ: He was not a business last year.
Nghi vấn: Was / Were + S + O ?
Ví dụ: Were you a teacher last month?