Learning and thinking, Chen Chen, teacher, high school mathematics league, high school, high school, high school, full course.
I have it here, but if I can't send it directly, it will be blocked. The video is exactly the same, but the price is a little lower. It can be placed on the phablet client or on the computer. Generally, this kind of thing costs a little money, and the price is around 20. If you can afford it, leave your contact information and I'll send it to you (much cheaper than learning and thinking)