You may not understand it, but it depends on your personal talent and mathematical understanding. However, you'd better make up the courses you left behind before, so that the study pressure in grade three will be less. In fact, a lot of math knowledge in junior high school is basically talked about in the first and second year of high school. The third grade can be said to be a review stage. Make up the previous lessons and do some exercises, which is probably enough. I think you will spend more time, so the landlord should be prepared to suffer.