• 13. He is a club member, but he rarely participates in activities.
• 14. Lan wants to join the school music club, but she is too busy.
• 15. She wanted to prepare for the exam, so she turned off her mobile phone.
• 16. We don't cheat on exams, because it is against the rules.
• 17. Phong has to study harder; otherwise, he may fail the exam.
• 18. She is very sensitive, so don't comment on her new hair.
• 19. Mi wants to have more friends, but she doesn't connect well with others.
• 20. Students can work in groups or in pairs.

You need to identify whether the sentences are simple or compound:

1. The dog barks. - Simple sentence
2. Men may come and men may go, but I go on forever. - Compound sentence
3. You should either sit quietly or go out. - Compound sentence
4. The kettle boils. - Simple sentence
5. You may watch TV or you can go out to play. - Compound sentence
6. Birds live in nests. - Simple sentence
7. The boys are singing. - Simple sentence
8. He is famous, yet he is very humble. - Compound sentence
9. The little girl was carrying a basket on her head. - Simple sentence
10. The thieves not only robbed the man of his possessions, but also inflicted injuries on him. - Compound sentence