Certainly! Let's tackle the various parts of your query step by step:

### Translation:

1. **Máy tính** - Computer
2. **Hộp đựng viết chì** - Pencil case
3. **Bữa trưa ở trường** - School lunch
4. **Môn học** - Subject
5. **Đồng phục** - Uniform
6. **Đẹp bảnh bao** - Handsome/Smart/Well-dressed
7. **Môn lịch sử** - History
8. **Bài tập về nhà** - Homework
9. **Bài tập, bài tập thể dục** - Exercise, Physical exercise
10. **Môn khoa học** - Science

### Verb Conjugation:

11. **It (be) a pen.** - It **is** a pen.
12. **My friends **(not be) friendly.** - My friends **are not** friendly.
13. **I and Mai (be) friends.** - I and Mai **are** friends.
14. **This (be) a book and these (be) pens.** - This **is** a book and these **are** pens.
15. **(be) you in class 4A?** - **Are** you in class 4A?
16. **They (go) home.** - They **go** home.
17. **My cousin (do) housework.** - My cousin **does** housework.
18. **Your mother (like) fish.** - Your mother **likes** fish.
19. **Her sister (chat) in their room in the evening.** - Her sister **chats** in their room in the evening.
20. **Your father (go) home from work at 9 p.m.** - Your father **goes** home from work at 9 p.m.

Let me know if you need further assistance or clarification!