`\text{Quá khứ đơn}`
$\text{Với ĐT to be: S + was(not)/were(not) + O.}$
$\text{Với ĐT thường:}$
$\textit{(+) S + Ved/VPI + (O).}$
$\textit{(-) S + didn't + Vinf + (O).}$
$\textit{(?) Did + S + Vinf + (O)?}$
`1.` was
`\text{nhận bt: In the past}`
`2.` were
`\text{nhận bt: an hour ago}`
`3.`Did `-` spend
`\text{nhận bt: last summer}`
`4.`wrote
`\text{nhận bt: last Monday}`
`5.` didn't come
`\text{nhận bt: last Sunday}`