1. I never saw it - I have never seen it
2. Sam has arrived - Sam arrived
3. My best friend and I knew - My best friend and I have known
4. She never saw - she has never seen
5. Travelling became - travelling becomes
6. It has taken - it took
7. You changed since the last time I've seen you - you've changed since the last time I saw you
8. Sportsmen have tried, nobody ever did - Sportsmen tried, nobody has ever done
9. I never visited Africa, I have travelled to - I have never visited Africe, I have been to
10. I have gone to - I have been to