Here are the correct answers for each question:

5. How can you live in this messy room? Go and ___ it up at once.
- A. dust
- B. sweep
- C. tidy
- D. do
- **Correct Answer: C. tidy**

6. We're good friends. We ___ each other for a long time.
- A. know
- B. have known
- C. are knowing
- D. knew
- **Correct Answer: B. have known**

7. John looked ___ today because he got mark 10.
- A. happy
- B. happily
- C. unhappy
- D. happiness
- **Correct Answer: A. happy**

8. There are not many ___ between American and British English.
- A. difference
- B. different
- C. differences
- D. differently
- **Correct Answer: C. differences**

9. You sometimes help your mother ___ the housework.
- A. with
- B. for
- C. about
- D. on
- **Correct Answer: A. with**