In English papers, the "introduction" is the introduction part, whose main function is to introduce readers to the theme, background, purpose and research problems of the paper, as well as the research status and research gaps in related fields.

Specifically, the main functions of the introduction part include:

1. Lead out the topic of the paper: The introduction usually briefly introduces the topic or title of the paper, so that readers can have a preliminary understanding of the research direction of the paper.

2. Background introduction: The introduction part will introduce the background information of the fields or problems involved in the paper, including the relevant historical evolution, present situation and development trend. To help readers understand the background and importance of the research question.

3. Explain the research purpose: The introduction will clearly explain the research purpose and problems of the paper, so that readers can understand the core content and key points of the research.

4. Literature review: The introduction will summarize the existing research results, introduce the research status and research gap, and provide theoretical basis and reference for the follow-up research.

5. Guide readers: The introduction will also briefly introduce the overall structure of the paper, help readers understand the content and relevance of each part, and guide readers to better understand and master the essence of the paper.

In a word, the introduction of English thesis aims to present the overall framework, research background and existing research results for readers, and provide theoretical support and practical reference for subsequent research.