`1`. Laurence last saw her sister when she left for Japan.

`2`. The last time Lucy wore that dress was Barbara's wedding.

`3`. My mother has worked at this school for `25` years.

`4`. This is the first time I have been to this entertainment park.

`@` Cấu trúc QKD <=> HTHT:

`-` This is the first time + S + have/has + V3/ed: Lân đầu tiên ai đó làm gì...

`=` S + have/has + not/never + V3/ed + before

`-` The last time + S + V2/ed + was + time + ago: Lần cuối ai đó làm gi vào thời gian nào...

`=` S + last + V2/ed + time + ago/when + Clause

`=` S + haven't/hasn't + V3/ed + for/since + khoảng thời gian/mốc thời gian

`-` S + started/began + toV/Ving + time + ago: Ai đó bắt đầu làm gì vào thời gian nào đó trước đây

`=` S + have/has + V3/ed + for/since + khoảng thời gian/mốc thời gian

`1,` Laurence last saw her sister when she left for Japan

`->` S + have/has + not + P2 + ... + since + t/gian

`=` S + last + V2/ed + ... + when + t/gian

`2,` The last time Lucy wore that dress was Barbara's wedding

`->` S + have/has + not + P2 + ... + since + t/gian

`=` The last time + S + V2/ed + ... + was + t/gian

`3,` My mother has worked at this school for `25` years

`->` S + started/began + to V/V-ing + ... + t/gian + ago

`=` S + have/has + P2 + ... + for + t/gian

`4,` This is the first time I have been to this entertainment park

`->` S + have/has + never + P2 + ... + before

`=` This is the first time + S + have/has + P2 ...