Attempt the question, check the explanation, and continue with similar questions to build confidence before exams.
A = {1, 2}, B = {2, 3}
A = {4, 5}, B = {5, 6}
A = {7}, B = {8}
A = {3, 4}, B = {3, 4}
Continue with nearby questions to strengthen the same chapter concept while you still have the context fresh in mind.