The learning methods of each course are different, and it is very likely that the learning ideas have not been adjusted well. Especially mathematics, sensory physics and biology, as long as you enter that thinking system, you will be more eager to learn. You must try more, don't buckle to death, and think more about how you will start if you study this problem.

Besides, don't have any burden. Learning well in junior high school is a thing of the past. Now it's time to start over. Ask someone else