`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.

`4,` I have not seen her for 2 weeks

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

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

`+` have/ has `+` not `+` V-3 `=` The last time + QKD + was + mốc thời gian + ago `=` It's + mốc thời gian + since ( kể từ khi ) + S + last + QKD

`+` since `+` mốc thời gian `=` for `+` khoảng thời gian ( 1 day, 2 days, 2 weeks, 4 years , ... )

`-` Đã 2 tuần kể từ khi tôi nhìn thấy cô ấy

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

`-` last `+` QDK `+` was `+` mốc thời gian ( in + tháng/năm/ngày/... )

`-` Lần cuối cô ấy mua chiếc xe đạp là vào 2015

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

`-` Lần cuối trời mưa là vào 3 tháng trước