单项选择题
A.9+2x B.9-2x C.4x-3 D.13-4x E.以上答案均不正确
A.40% B.45% C.50% D.55% E.60%
A.m<2 B.m≤2 C.m≥2 D.m>2 E.以上结果均不正确