At the same time, I also bought RAZ. In this series, I personally feel that the difference between Pearson English and Oxford is more inclined to the British grading system, while this RAZ is more inclined to the American problem system. The specific system is the American GRL grading system, which can be said to be a more detailed and accurate problem system for American children's enlightenment. So in the end, my children and I are more inclined to interact with children than to use Oxford, and more inclined to interesting stories. In the United States, rac is more inclined to the whole scientific system, so that children can understand the whole foundation of English a little bit.