16 Is |x – y| > |x – z|?

(1) |y| > |z|

(2) x < 0

17 In a set of 400 integers, is the sum of them greater than 0.1?

(1) The greatest one is less than 0.0002.

(2) The sum of greatest 50 integers is 0.01.

18 If points (a,b) and (c,d) are on line k, is the slope of line k positive?

(1) a < c, and b < d.

(2) The product of x--‐intercept and y--‐intercept is negative.

19 If 3^x – 3^(x – 3) = 26/3^9, what is the value of x

A. 6

B. --6

C. 9

D. --9

E. 13

20 If x and y are integers, what is the value of (x + y)^2?

(1) x = y – 3

(2) x and y are prime numbers.

答案：

16. E

17. D

18. D

19. B

20. C