在平面直角坐标系中，函数y=﹣x+1的图象经过[ ]
A．一、二、三象限
B．二、三、四象限
C．一、三、四象限
D．一、二、四象限
答案：D
I spent a _____ vacation, so I'm _____ now.[ ]
A. relaxed; relaxing
B. relaxing; relaxing
C. relaxing; relaxed
D. relaxed; relaxed
迷宫式汽封最常用的断面形式是那两种？各有何优缺点？
