you learned the work and then learned how to pass the exam. Two quite distinct areas of endeavour.
There are only so many questions on a particular subject that can realistically be asked by the CASA testing staff without going overboard. When they run out of ideas, perhaps because the same question (s) have appeared months or years earlier in the exam cycles, then the same questions will eventually reappear in some slightly changed form or other in later exams on that specific subject. That form or other is then cunningly twisted slightly, where one word or one sentence makes all the difference between a pass or fail - even though the candidate may know his subject backwards. It has been forever so. Change or even omit one word in a multi-choice question, and although you may know that subject well enough to pass through sheer knowledge, the candidate is foiled again. That is why the FAA system of offering the candidate a large bank of questions to study and none are trick questions, then it is in the interest of the candidate to study the lot before fronting for a written or oral test