Exercise 2 I. 1, A 2, C 3, D 4, C 5, C 6, B 2, 7, WWW 8, 5 9, 2 10,11,5/kloc-0.

Exercise 3 I, 1, D 2, B 3, D 4, C 5, C 6, A 7, D 8, B 2, 9, (4)(6)(7), (1) (2) (3) (5)1.

Exercise 4 1, 1, B 2, C 3, D 4, D 5, D 6, A 7, B 8, B 2, 9, negative half, plus or minus 3 10, negative root number 5, root number 3- root number 21,.

Exercise 5 I, 1,,, C4,, D6, C7, C8, A9, C2, 10, 3601,I, Kou, Wang Tian 12, pass the intersection.

Exercise 6 I, 1, B2, C3, A4, A5, D6, A7, C8, D II, 9, line segment, parallelogram, square and circle; Line segment, angle, square, isosceles trapezoid, circle, equilateral triangle; Line segment, square, circle 10,1351,AD is parallel to BC 12, 80 13, 5 14, 35.

Exercise 7 I, 1, D2, B3, C4, A5, B6, A7, A II, 8, a pair of ordered real numbers 9, 13 10, 31,(-3,-

Exercise 8 1. 1，B2，C3，A4，C5，B6，C 2，7，(3，0)； (0, 1); (minus six sevenths, minus nine sevenths) 8, y=x+39, s=264-24t 10, -2 1 1,-12, y = x-.