1. Problem solving: The purpose of choosing a topic is usually to solve a specific problem or challenge. Through in-depth research and analysis, the root of the problem and the solution are found, which provides valuable reference for the development of this field.

2. Promote development: The purpose of selecting a topic can also be to promote the development of a certain field. Through the in-depth study of the basic theory, applied technology or policy measures in a certain field, we can provide new ideas and directions for the development of this field and promote its progress and development.