Sure! Here are the correct forms of the words to fill in the blanks:

IV. Write the correct form of the word to fill in the blank:
1. We have two postal **deliveries** a day.
2. He left the room without **explaining**.
3. Playing tennis is one of his favorite **activities**.
4. We started our trip on a beautiful **sunny** morning.
5. They left the house in a **frightening** mess.
6. He said “Good morning” in a most **friendly** way.
7. There is no easy **solution** to this problem.
8. He always drives more **carefully** at night.
9. Does this **arrangement** suit you?
10. He is a very **skilled** carpenter.

V. Find the incorrect word and correct it:
Nam is a student. This year he had a very **interesting** summer holiday. He traveled, with **his** classmates, to a mountainous area in Hoa Binh province. They **went** there to help make a road through a forest **between** two villages. “It was very difficult because there **was** no water to drink and no shops where we could **buy** food,” said Nam. “It was very cold and wet in the mountains. It **is** one of the **wettest** places in the country.” Nam stayed in the mountains **for** six weeks. It was hard work. But he says it was the best thing he has ever **done**. He is hoping to return next year to do **some** more work there.