1. How long have you been here? I've been here three days since last Thursday. 2. Have you ever travelled by sea? 3. We have never been to Australia. 4. They haven't packed their luggage yet. 5. Have you bought a return ticket yet? 6. They have just arrived at the airport. 7. Have you seen Oleg today? 8. Have you heard from Jane this week? 9. They have recently visited five foreign countries. 10. I am not sure he has already caught flight 415.