a mixed class的用法和样例：
- In a mixed class, boys who might do well in a single-sex class become discouraged and take on the role of troublemaker.
- She was so busy that she was in a mix.
- A mix of people attended the meeting.
- Tastes like a mix of cinnamon and vanilla.
- There is a mixed doubles this afternoon.
- The songs on this record are quite a mixed bag.