To write about your English proficiency in junior high school, you can describe your grades, improvement over time, and any specific skills or achievements. Here's an example:

In junior high school, my English grades were consistently high, often scoring above 90% on exams and assignments. I worked hard to improve my vocabulary, grammar, and reading comprehension, which led to a significant increase in my scores from the beginning to the end of the three-year period. My oral communication skills also saw considerable progress as I participated actively in class discussions and presentations. Additionally, I excelled in creative writing, receiving praise for my essays and short stories. These accomplishments not only reflected my dedication to the subject but also laid a solid foundation for further studies in English language and literature.