`1.` Lan didn't write to Maryam a month ago.

`2.` I didn't meet her a long time ago.

`3.` How long ago did you learn French?

`4.` How long have you started to listen to classical music?

`5.` I haven't seen him since June.

`---------------`

`-` S + have/has not + P2 + for + time

`=`  S + didn't + V-bare + time + ago

`-` How long + have/has + S + P2?

`=` How long ago + did + S + V-bare?

`=` When + did + S + start + V-ing/to V?

`-` The last time +  S + Ved/V2 + was + in + time

`=` S + have/has not + P2 + since + time

`color{red}{#lgdr}`

`1` Lan didn't write to Maryam a month ago .

`-` a month ago : Quá khứ đơn .

`=>` S + did + not + V-inf + O .

`2` I didn't meet her a long time ago .

`-` a long time ago : Quá khứ đơn .

`=>` S + did + not + V-inf + O .

`3` How long ago did you learn English `?`

`-` ago : Quá khứ đơn .

`=>` Wh_question + did + S + V-inf + O `?`

`4` How long have you listened to classical music `?`

`-` Hiện tại hoàn thành : Wh_question + have/has + S + V3/Vpp + O `?`

`5` I have not seen him since June .

`-` since + mốc thời gian : Hiện tại hoàn thành .

`=>` S + have/has + not + V3/Vpp + O .