Answer :

1. dogs are animal

2. potatoes are vegetables

3. we are students

4. we are doing our homework

5. they are studying

6. the them herself writer the letter

7. business consist of operation

8. they perform services by answering Question

9. what are difference between you & us ?

10. they friend a also our friend

11. the students have almost finished doing them

12. have they ever been studying abroad

13. the earthquake cause great disaster

14. do they understand the lesson?

15. they are boys & girls in the class.