1, 0 is neither correct nor irresponsible; -a is not necessarily negative, and +a is not necessarily positive; P is not a rational number.

2. Absolute value: the absolute value of a positive number is itself, and the absolute value of a negative number is its inverse; The absolute value of 0 is 0, two negative numbers, the larger absolute value is smaller.

3. When there is a division operation in the algebraic expression, the division method and the division method are generally connected by a fractional line, such as in the form of 3÷a writing. ..

4. Among rational numbers, 1, 0 and-1 are three special numbers with their own characteristics; These three numbers divide the numbers on the number axis into four areas, and the numbers in these four areas also have their own characteristics.

5. Function of the number axis: All rational numbers can be represented by points on the number axis.