In order to learn, people teach online. "Learning without thinking is useless", and thinking is the soul of learning. In learning, knowledge is important, but it is more important to control the knowledge mind. If a person can't think, he can only be a slave to knowledge. No amount of knowledge is useless, and it is impossible to really learn good knowledge. Knowledge learning focuses on understanding, and understanding can only be achieved through thinking. The source of thinking is the problem. In learning, we should be careful not to let go of any problem easily. When we encounter a problem, we should try our best to think independently and use our brains to find the correct answer to the problem. Only in this way can we improve our thinking ability.