Find the seventh grade Olympic math problem and its answer

Mathematics problems in the first grade of junior high school

1. Among the following conclusions, the correct one is (d).

A. If a number is an integer, it must be a rational number.

B. If a number is rational, it must be an integer.

C. If a number is rational, it must be negative.

D. If a number is rational, it must be positive.

2. If the reciprocal of the reciprocal of a number is a natural number, then the number is ().

A.b .-c . 3d .-5

3. if a? b