A:would be freezing cold
B:would be frozen cold
C:would be freezing coldly
D:can freeze coldly
金秋十月,某地学校地理兴趣小组开展了一次家乡地理调查,并绘制了等高线地形图(乙).根据图文材料,回答问题.
在平面直角坐标系中,对于点P(x,y),我们把点P′(﹣y+1,x+1)叫作点P的伴随点.已知点A1的伴随点为A2,点A2的伴随点为A3,点A3的伴随点为A4,这样依次得到点A1,A2,A3,A4…,若点A1的坐标为(a,b),对于任意的正整数n,点An均在x轴上方,则a,b应满足的条件为____.