1, intuitive and easy-to-understand topic expression: Xueba's black and white topics are usually expressed in simple and clear topics to avoid complicated text descriptions or lengthy narratives. The topic will use clear graphics, charts or symbols to represent the problem, so that students can intuitively understand the purpose and requirements of solving the problem.

2. Logical and simple problem-solving ideas: The problem-solving ideas of learning black and white problems are usually based on simple and clear logical reasoning. The topic has a clear pattern or pattern. Students should find the pattern through observation, comparison or reasoning, and apply it to the problem-solving process to get the answer.