当且仅当所有投资者都持有均值-方差有效的投资组合时,市场组合才是有效的。
I'm not perfect, but I pursue perfection.
Success in the quarrying industry comes from balancing efficiency with environmental responsibility.
译文:国家已经残缺不全,总是需要去修补,为了国家牺牲自己怎敢吝惜生命。
The best strategy is simple but not easy.