1. Of the following operations, the correct one is .......................................... ().
A, B, C, D,
2. If 9-MX+X2 is a completely flat mode, the value of m is ....................... ().
A.3 B.6 C. 3 D. 6
3. In order to understand the time spent by the seventh-grade students in our district on their studies every day, 300 of them were investigated. The following statements are incorrect: ........
A. Generally speaking, it is the sum of the time spent on study by the seventh-grade students in our district every day.
The time that 300 students spend studying every day is a sample of the whole population.
C. The sample size is 300 d, and the individual is 1 the study time of students every day.
7. If 0.0000102 =1.02×10n, then n is equal to ..................... ().
A.-3 B.-4 C.-5 D.-6
II. Fill in the blanks (this big question * * 10 small question, 2 points for each small question, 20 points for * * *)
9. The following four calculations: ①, ②, ③, ④, in which _ _ _ _ _ _ _ _ _. (Fill in serial number)