* Past simple:
- To be:
(+) S + was/were + N/Adj
(-) S + was/were + not + N/Adj
(?) Was/were + S + N/Adj ?
- Động từ thường:
(+) S + V(ed hoặc c2)
(-) S + didn't + V(bare)
(?) Did + S + V(bare)?
* Past continuous:
(+) S + was/were + V_ing
(-) S + was/were + not + V_ing
(?) Was/were + S + V_ing ?