题目

设a、b都是非零实数，y=++可能的取值组成的集合为（    ）A.{3}            B.{3,2,1}          C.{3，1，-1}              D.{3，-1} 答案：解析：根据两个字母的符号分类讨论即可得出答案D，在讨论的过程中，注意集合元素的互异性.答案：D --Shall we play basketball this afternoon? --         I need to exercise very much． A．Why not?                                                B．I agree with him． C．You are lucky．                                         D．No，I don't want to．