First, multiple-choice questions.

On the number axis, the number represented by the point from the origin 3 is ().

A.-3，B. 3，C. -2，D. 2 .

Point m is the point on the number axis that represents -2. If the point m is translated 5 units to the right along the number axis to the point n, the number represented by the point n is ().

A.-7，B- 3，C. 3，D. 7 .

If a+b > 0 and ab < 0, then ().

A.a>0，b>0，B. a