Natural experiments can provide valuable insights into economic questions.
Success is no accident. It is hard work, perseverance, learning, studying, sacrifice and most of all, love of what you are doing.
嗨，我是科比-布萊恩特，我已經(jīng)決定把我的天賦帶到......額，我決定跳過(guò)大學(xué)，把我的天賦帶到NBA。
景觀不僅僅是其組成部分的總和，而是一個(gè)復(fù)雜系統(tǒng)，其中每個(gè)元素都是相互關(guān)聯(lián)的。