1. 认识这个词（基础篇）
词：boil down to
英英释义：to be the main reason for something or the most basic part of something
例句：Big, sweeping life changes really boil down to small, everyday decisions.
2. 体会这个词 （进阶篇）
“boil down to”是个出现频率很高的实用表达，可以用在口语和写作中。它的意思是“一个问题的主要原因是、归根结底是”，如同熬一锅汤，煮时间长了水分就会减少，只留下最重要最本质的东西。当我们想表示一个事件的本质时，就可以用到它。
比如我们想说主要问题是缺钱，就可以用 boil down to something 造句：
The problem boils down to one thing: lack of money. (这里的冒号也可以换成破折号，或者也可以直接说成 The problem boils down to lack of money.）
亚马逊 CEO 杰夫·贝佐斯曾在一次毕业典礼中说“In the end, we are our choices.“ 我们可以用 boil down to 来改写这句话：
Ultimately, who we are boils down to our choices.
美国一位减肥比赛节目冠军 Ali Vincent 说过一句类似的话：
Big, sweeping life changes really boil down to small, everyday decisions.
我们在口语中可以常用 It all boils down to 这个简单句型，表示“归根结底就一件事儿“，比如：
It boils down to one thing: who you know in this business.
It boils down to one question: do you really want to learn English well?
It boils down to a simple question: do you really love me?
The question will always boil down to: who pays for the extra cost, and takes the initial risk? （来自《经济学人》，在讨论市场机制、监管等话题的文章中直接使用）
和 boil down to 类似的常见同义表达是 come down to，在掌握了 boil down to 的用法之后，可以学习一下 come down to 的用法。
3. 从认识到会用（作业）
1）翻译下面的句子：
这场争论归根结底是伦理问题而不是法律问题。
The argument boils down to ethics rather than laws.
（参考翻译：The argument boils down to ethics rather than laws.）
2）结合自己的生活、学习、工作、兴趣等，想象在什么语境下会用到这个表达。先简要描述这个场景，再造句。
场景： 人物
造句：When he was 52,with a hand that still trembled, Vann Nath produced a painting of a young man lying under a blossoming tree. He was playing a pipe while, in the background,cattle grazed by green palms in some bucolic corner of Cambodia. It was meant to be a self-portrait, he said, a beautiful memory from his childhood. He wanted only to paint idyllic landscapes now, in the style of temple murals or the French Impressionists who had first inspired him to take up art. That was because, in 1978-79, he had been made to paint quite different pictures. In those months he was interned in S-21 prison, a former French lycee in Phnom Penh which had been converted into a torture-compound for alleged enemies of the Khmer Rouge regime. Perhaps 14,000 people were sent to S-21 for a daily routine of electrocution, water-boarding and flagellation before being carted off for execution-a shovel or spade to the head-at the nearby ”killing fields”. Mr.Vann Nath was one of only six or seven prisoners to make it out alive. He was asked to paint portraits of the regime’s leader Pol Pot. All the time he painted, day and night, the screams of the tortured echoed from other rooms. He hoped, with every brush-stroke, that his jailers would like his work and lethim live. His ability to focus boiled down to the desire to kill the man he drew. Nonetheless, he carried out the task to the satisfaction of Duch, the prison commandant. For his flattering portraits, giving Pol Pot a fresh-faced girl’s rosy cheeks.