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.

The method of junior one mathematics:

Classroom exercises, homework, tests and feedback should be consulted in time, the causes of wrong questions should be analyzed, and relevant calculation training should be strengthened when necessary. Ask your classmates and teachers if you don't understand. Don't let the problem hang in the air. Get into the good habit of doing things today.

Mathematics and mathematics are closely related, and so is knowledge. Summing up by stages can not only play a role in reviewing and consolidating, but also find the connection between knowledge, so as to achieve a thorough understanding.