实现消费者均衡的前提条件是( )。
A．偏好不变
B．收入不变
C．支出不变
D．价格不变
E．市场环境不变
参考答案：A,B,D
Much to our , the result of the experiment was much better than we had expected. [ ]
A. satisfactory
B. satisfaction
C. satisfied
D. satisfy
对角线相等，并且互相垂直平分的四边形是（ ）
A．等腰梯形
B．矩形
C．菱形
D．正方形
