你必须能够直面现实,同时也要激发希望。
are a soldier, do not fight for my freedom. Fight for the freedom of the soldier fighting next to you. This will make the war more inspiring for you both.
理解布莱克-斯科尔斯模型的关键在于认识到它是基于风险中性世界的概念,在这个世界中投资者对风险漠不关心。