English grammar: thick grammar books, do exercises. High school grammar is detailed enough. Many people on the Internet recommend the grammar club written by Mr. Yuan You.

English pronunciation: correcting pronunciation and intonation is a long-term process, but you can learn some rules such as phonetic symbols, linking and stress. American accent training is highly recommended online, and you can learn from this book.

Advanced English: the extension of intensive reading course, but the difficulty of the text will be greatly improved, mainly to appreciate the beauty of the article. Zhang Hanxi's advanced English textbook is recommended, which is said to be the classic among the classics.