Sure! Here are the completed sentences:

1. There are lots of beautiful lakes in Viet Nam.
Viet Nam **has a lot of beautiful lakes**.

2. Our country doesn't have any deserts.
There **are no deserts in our country**.

3. Mr Hung is Nam's teacher.
Nam **is taught by Mr Hung**.

4. Remember to do your homework.
You must **do your homework**.

5. Quang sits in front of Minh.
Minh **sits behind Quang**.

6. It's good if children go to bed early.
Children should **go to bed early**.

7. My favourite room in the house is the living room.
I like **the living room the most in the house**.

8. We have a sink, a fridge, a cooker and a cupboard in our kitchen.
There **is a sink, a fridge, a cooker and a cupboard in our kitchen**.

9. The notebook is on the book.
**The book is underneath the notebook**.

10. During Tet holiday, Thanh Hoa is much cooler than Binh Duong.
During Tet holiday, Binh Duong **is not as cool as Thanh Hoa**.

Feel free to ask if you need more help!