This problem is a common phenomenon among students today. Many people call this phenomenon sloppy, which is actually incorrect. I think everyone's carelessness is that they don't have a good grasp of formulas and theorems. For some of your symptoms, it is also possible that some of the reasons for these symptoms are nervousness. Before each exam, you can adjust your mental state, face the exam calmly, cheer yourself up, have confidence in yourself and do it together. It is unwise to study a problem repeatedly, and time is not allowed. Besides, your answers to the paper are inconsistent, which should be because you are neat and tidy on the paper. Because it's paper, it doesn't have to be as neat as what is written in the exercise book, but at least let yourself see it clearly. If you can do it all, your grades will definitely improve. I wish you early success.