債券市場是世界上最重要的市場。
非經(jīng)典邏輯的研究不僅是一種學(xué)術(shù)練習(xí),更是理解復(fù)雜系統(tǒng)的必要條件。
The farmer is the only man in our economy who buys everything at retail, sells everything at wholesale, and pays the freight both ways.