阅读下列短文，从每小题的三个选项中选出最佳答案

      It is morning now. Look at the sun, it rises in the east(东方). Look at the tree, the shadow is long. It is noon now. The sun is high in the sky. It is very hot. Look at the tree. The shadow is short. It is evening now. The sun goes down in the west(西方). Look at the tree, the shadow is long again. It is night now. The moon is high in the sky. There are some stars in the sky too.

这次改革对北魏有什么影响？

许多历史学家认为，古罗马曾有三次影响世界，第一次以武力，第二次以宗教，第三次以法律。武力因罗马帝国的灭亡而消失，宗教随着人们思想进步和科学发展而缩小了影响，唯有第三次以法律才是最为平和、最为持久的影响。

已知 $f\left(x\right)=\left|x+a\right|,g\left(x\right)=\left|x+3\right|-x$ ，记关于 $x$ 的不等式 $f\left(x\right)<g\left(x\right)$ 的解集为 $M$ ．

“不登高山，不知天之高也；不临深溪，不知地之厚也。”相对于学习来说，这表明（　）