Friends are better than money. Almost anything money can do， friends can do better. In so many ways a friend with a boat is better than owning a boat.

柠檬问题是指买家无法确定产品质量，因此只愿意支付反映平均质量的价格。

教育者的心必须是一团活生生的火焰，是温暖和光明的源泉。