IV.
1. I have learned English for three years (Started to V.inf ⇒ Have V(ed/P2)
2. She began to write her pen pal five years ago (Has V(ed/P2) ⇒ began to V.inf)
3. It is three years since Lan and Maryam corresponded (It is + time + since + QKĐ)
4. It's the first time I have won this shirt ( It's the first time + S + has/have + V(ed/P2).
5. The last time I heard him was August ( The last time + QKĐ + was + time)
6. He hasn't gone aboard before ( He + has + not + V(ed/P2) + before