1, seriousness: writing with a black pen or pen can reflect the solemnity and seriousness of the application and leave a deep impression on people.
2. Clarity: Writing with a black pen or pen can improve the clarity of the font and make it easier for readers to understand the content of the application.
3. Reliability: Writing with a black pen or pen can enhance the credibility and authority of the application and make it more convincing and appealing.