6. Let's collect unused clothes.

7. Because she was lazy, she failed the exam. 

8. Ba is tired because he stayed up late watching TV. 

9. Since Hoa was careless, she broke the cup.

10. Since It rained , we have decided to postpone our camping.

11. She was busy, so she couldn't join with us.

12. What about going to the cinema tonight?

13. Shall we use energy-saving bulbs? 

14. She wasn't beautiful but she took part in a beauty contest.

15. If you work hard, you will pass the exam.

16. Unless you start working hard now, you will be able to pass the final exam.

Bạn làm như sau:

6-Let's collect unused clothes.

7-Because she was lazy, she failed the exam. 

8-Ba is tired because he stayed up late watching TV. 

9-Since Hoa was careless, she broke the cup.

10-Since It rained , we have decided to postpone our camping.

11-She was busy, so she couldn't join with us.

12-What about going to the cinema tonight?

13-Shall we use energy-saving bulbs? 

14-She wasn't beautiful but she took part in a beauty contest.

15-If you work hard, you will pass the exam.

16-Unless you start working hard now, you will be able to pass the final exam.

Đây là bài làm của mình mong bạn tham khảo ạ và chúc bạn học tốt nhé!