If you have any questions that you can't answer in the future, go to "seek answers". The question bank is huge, and almost all the questions that can't be done can be found. There are all kinds of questions about mathematics, physical chemistry, especially the mid-term exams, simulation questions, textbooks and the answers are very detailed. There are similar problems without the original title, and the interface is very scientific. Let's go
There is also a high school version that was recently launched. You can answer all kinds of high school math, physical chemistry questions, including junior high school math, physical chemistry and biology questions and senior high school math, physical chemistry and biology questions.