哪种模型把政策过程假定为输入——决策——输出——反馈这一系统运行过程。（）
A．政治系统
B．精英主义
C．混合扫描
D．规范最佳
参考答案：A
— Cathy, I have cleaned the room for you.
— Thanks. You _____ it. I could manage it myself. [ ]
A. didn't need to do
B. needn't have done
C. mustn't do
D. shouldn't have done
下列不属于毒品的是（ ）
A．鸦片
B．大麻
C．海洛因
D．硝酸甘油
