=>
15. While we were talking about Linda, she came up.
-> while QKTD, QKĐ
16. At the Ooc om bok we float beautiful paper lanterns on the river, and we also hold thrilling dragon boat races.
-> and : và
17. My aunt and uncle live in Ho Chi Minh City; however, they go to the Bai Dinh Pagoda Festival in Ninh Binh Province every year.
-> however : tuy nhiên
18. In Viet Nam children have to wear uniforms at school.
-> have to V : phải làm gì
19. You should not stay up late to watch TV.
-> should not V : không nên làm gì
20. Because there are more and more cars sold every day, the traffic in the streets is becoming more and more difficult.
-> because S V : bởi vì