You know the proverb, Smile and the world smiles with you, cry and you cry alone.
要知道有句格言“微笑,世界与你同欢乐;哭泣,你只能独自悲伤”。
As is so often pointed out, knowledge is a two-edged weapon which can be used equally for good or evil.
正像人们常常指出的,知识是一把双刃刀,可以用于造福,也可以用来为害。