重点讲解：
1. make money
挣钱；赚钱；
eg. They couldn't find work or make money in the cities.
他们在城市找不到工作，也赚不到钱。
eg. He was a businessman, and therefore he always has an eye out for any opportunity to make money.
他是商人，总见钱眼开。
2. down to
只剩下；
eg. The poor man's down to his last £3.
那个可怜的人身上只剩 3 英镑了。
eg. He was already down to his last loaf of bread.
他已经穷得只剩下最后一个面包了。
3. invest in
购买；买进；
eg. The company invested thousands in an electronic order-control system.
公司耗资数千购买了一套电子订单管理系统。
eg. The easiest way to make ice cream yourself is to invest in an ice cream machine.
自己制作冰激凌的最简单的办法就是买一台冰激凌机。