Решение:
Сопоставим идиомы с их определениями:
- To do something by oneself — B. To perform a task alone, without any help from other people.
- To make oneself heard — C. To talk with a loud enough voice.
- To enjoy oneself — E. To spend time well.
Дополнительные определения:
- A. To serve food on one's own.
- D. To act in a proper way.
Ответ: 1-B, 2-C, 3-E.