`4,`

`->` I haven't seen her for `2` weeks.

`->` The last time I saw her was `2` weeks ago.

`->`  It's `2` weeks since I last saw her.

`@` S + last+ V2/V-ed+O + khoảng thời gian + ago.

`=` S+has/have+not+ V-pp+O+ for+ khoảng thời gian.

`=` The last time +S+ V2/V-ed+O + was + khoảng thời gian + ago.

`=` It's + khoảng thời gian +since+ S+ last+ V2/V-ed+O.

`5,`  She last bought the bike in `2015.` 

`@` S + has/have+ V-pp+O +since + mốc thời gian/  năm/ thế kỷ.

`=` S+ last + V2/V-ed+O+ in + năm/thế kỷ / when + mốc thời gian.

`6,` The last time it rained was `3` weeks ago.

`@` It's + khoảng thời gian +since+ S+ last+ V2/V-ed+O.

`=` The last time +S+ V2/V-ed+O + was + khoảng thời gian + ago.