`1,` Quá khứ đơn:
- I didn't have enough money.
Cấu trúc: S + did/didn't + V-inf.
`2,` Quá khứ tiếp diễn:
- I wasn't having enough money.
Cấu trúc: S + was/were/wasn't/weren't + V-ing.
`3,` Quá khứ hoàn thành:
- I hadn't had enough money.
Cấu trúc: S + had/hadn't + V-p`2`.
`Envimiist`