`1.` We haven't traveled abroad since years.
- It's + time + since + S + last + V2/V-ed + ...
`->` S + haven't/hans't + VpII/V-ed + ... + since/for + time
`2.` It's 5 years since I last saw her.
- S + last + V2/V-ed + ...
`->` It's + time + since +S + last + V-ed/V2 + ...
`3.` It's ages since I last saw him.
- S + haven't/hans't + VpII/V-ed + ... + since/for + time
`->` It's + time + since + S + last + V2/V-ed + ...
`4.` We have become close friends for a long time.
- Vì ko có last nên ta dùng dạng khẳng định (have/has)
`5.` I haven't spoken to her for three years.
- It's + time + since + S + last + V2/V-ed + ...
`->` S + haven't/hans't + VpII/V-ed + ... + since/for + time