First, multiple-choice questions.

1. The following statement is true ()

① Rational number can be an integer or a fraction ② Rational number can be a positive number or a negative number.

Integer can be positive or negative. The score can be positive or negative.

A 1 B 2 C 3 D 4

2. The following statement is true ()

①0 is a rational number with the smallest absolute value ② The number whose reciprocal is greater than itself is a negative number.

③ The numbers on both sides of the origin on the number axis are opposite; ④ Compared with the two numbers, the absolute value is larger but smaller.

A ①② B ①③ C ①②③ D ①②③④

3. The following operation is correct ()

a-5/7+2/7 =-(5/7+2/7)=- 1 B-7-2×5 =-9×5 =-45

C3÷5/4×4/5 = 3/ 1 = 3d-(-3)2 =-9

4. If A+B < 0 and AB < 0, then ()

A a>0，b>0 B a