Test errors are usually from poor test taking strategies, such as failing to understand the format of a test question, or a failure to adequately prepare. Questions from early examinations are often repeated on a midterm or the final exam as instructors want to see if you have developed your knowledge from the earlier period. In addition, many courses are structured so that material builds upon knowledge so if you have a poor knowledge of the essentials, you will continue to struggle.
There is something you can do! Analyzing returned coursework can help you: