`13.` She started cooking for dinner two hours ago.

`->` S + started + V-ing + time + ago

`=` S + have/has + P2 + for + time

`14.` 

`-` I last saw a movie a long time ago.

`-` The last time I saw a movie was a long time ago

`-` I haven't seen a movie for a long time.

`->` S + last + Ved/V2 + time + ago

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

`=` The last time + S + Ved/V2 + was + time + ago

`=` It's + time + since + S + last + Ved/V2

`15.` 

`-` They haven't visited me for five years.

`-` It's five years since they last visited me.

`-` The last time they visited me was five years ago.

`->` như câu `14`