Exercise 11:
1. I have never talked to a foreigner before.
2. Ho Chi Minh City is the most crowded city in Viet Nam.
3. It's the first time we have ever tasted fish and chips.
4. Living in Hai Phong is more expensive than living in Bac Giang.
5. I haven't seen Peter for five months.
Exercise 9:
1. A 6. A
2. B 7. C
3. B 8. B
4. A 9. B
5. A 10. B