I am invisible, yet I make things clear, I can be shallow or deep, bringing distant things near. In silence, I speak, and in stillness, I show, reflecting both light and the darkness below. Without me, you stumble, yet too much and you’re blind, always ahead, but often behind. What am I?" c; n4 c* l, F, O" \& g6 L(欢迎访问老王论坛:laowang.vip)