First, multiple-choice questions. 1. The correct number in the following statement is () ① Rational number is not an integer or a fraction; ② Rational number is neither positive nor negative; ③ Integer is neither positive nor negative; ④ A score is neither positive nor negative A 1B2C3D42. A and B are rational numbers, and their corresponding points on the number axis are as follows: arrange A, -a, B and -b in descending order () A-B.