In English, a topic sentence is usually the core content of an article or story used to express the theme or idea of the article or story. It usually appears at the beginning of an article or story to guide the reader to understand the main content of the article or story. Compared with the Chinese topic sentence, the English topic sentence is usually more important because it directly express the theme or idea of the article or story. In Chinese, the main sentence is usually the core of the whole article or story, used to summarize the main idea or idea of the article or story. Therefore, although the topic sentence in English and the topic sentence in Chinese are both used to express the theme or idea of the article or story, they are different in expression. The topic sentence in English focuses more on directly expressing the core content of the article or story.