Here are the best answers for each blank in the passage:

9. Last year, I **B. to go** to a children's village in Yen Bai with my teachers and friends.

10. Don't **B. stay in** late. You should go to bed early. It's good for your health.

11. Breakfast is the **C. main** important meal of the day.

12. ...the calories it needs for **C. energy** and helps to maintain your blood sugar level.

13. ...are often slow, tired, hungry and **A. able** to concentrate. (However, "unable" may fit better contextually, but based on the given options, "able" is the only one that fits grammatically.)

14. It’s easier to **D. lose** weight if you eat in the morning rather than later in the day.