1. This is mine, not yours.

Đại từ sở hữu = tính từ sở hữu + N

2. I am standing in front of some people waiting to go inside the gallery.

behind: đằng sau >< in front of: đằng trước 

3. Before you go shopping, you should make a shopping list. 

Before + clause, clause: trước khi ... 

4. The rich girl rarely checks price tags when buying brand-name clothes.

ADV chỉ tần suất + V 

S số ít + Vs/es: thì HTĐ

5. He told me that he was watching a film about future life on TV then.

S + told + O + (that) + S+ V (lùi thì)

HTTD --> QKTD

now --> then 

6. Mai said that she would read some scientific books the next week.

S + said + (that) + S+ V (lùi thì)

will --> would 

next week --> the next week / the following week 

7. When the bell rang, everyone raced out of the classroom.

When + QKĐ, QKĐ

8. Mr. Nam is a teacher of mine.

a + N of + dtsh 

9. He said that his wife had just come back from Sweden.

S + said + (that) + S+ V (lùi thì)

HTHT --> QKHT

10. Lan said that she didn't have any knowledge about the Nung ethnic group.

S + said + (that) + S+ V (lùi thì)

HTĐ --> QKĐ

11. Can I use a hat of yours? 

a + N of + dtsh 

12. Mike and John are two foreign friends of mine.

số lượng + N + of + dtsh 

13. Nam is playing football with a classmate of his.

a + N of + dtsh 

`color{orange}{~MiaMB~}`