y = f(x) 的图像：1.y = f(x + a) -----------水平向左平移 a 个单位；2.y = f(x - a) -----------~；3.y = f(x) + b -----------垂直向上平移 b 个单位；4.y = f(x) - b -----------~；总而言之：y = f(x + a) + b ...