Hello Lijin. I dont think its a good idea to rely soley on the question banks. Its still really important you study the 3rd class books. I have written 3 of the 4 3rd class exams using the Powerengineering101 course and test banks with great success. The exams this year dont include all the material thats in the books and its not an even balance of questions from each chapter. On the 3A1 exam 44 of the 100 questions were on thermodynamics. It had zero questions on geometry. I will attach pics of the exam breakdowns for you to see. Good luck with the rest of your exams.