因为贫困没有独一无二的定义，重要的是将贫困线划在合理的位置，保持这条线的真实（经通胀调整的）水平不变，以便我们追踪世界和个体国家不同时间的表现。
Because there is no unique definition of poverty, what matters is to draw a line at some reasonable place and then hold the line constant in real (inflation-adjusted) terms so that we can track the performance of the world and individual countries over time.