break down
[phrasal verb] 1
a of a machine : to stop working properly（机器）损坏，出故障 — see also 1break 4 (above) b : to fail or stop usually in a complete and sudden way失败；突然停止 -
Negotiations have broken down. [=collapsed]谈判已经破裂。
-
The government's argument broke down completely when new evidence came to light.新证据一经曝光，政府的辩解就完全站不住脚了。
-
Their marriage had broken down [=failed], and there was nothing to do about it.他们的婚姻已经破裂，无法挽救了。
2
a : to become overwhelmed by strong emotions感情失控；感情崩溃 — see also 1break 8c (above) b break down or break (someone) down or break down (someone) : to lose or cause (someone) to lose strength or the ability to resist or fight（使某人）垮掉，变得衰弱 -
The prisoner finally broke down under intensive questioning.在强大的审问攻势下，囚犯的精神防线终于崩溃了。
-
She finally broke down and got a cell phone. [=she bought a cell phone after resisting the desire to buy one for a long time]她最终禁不住诱惑，还是买了一部手机。
-
Intensive questioning finally broke the prisoner down.强大的审问攻势最终使囚犯精神防线崩溃。
— see also 1break 8b (above) 3 break down or break (something) down or break down (something)
a : to become separated or to separate (something) into simpler substances（使）分解 -
The foods you eat break down in the body's digestive system.吃下去的食物在消化系统中分解。
-
The body's digestive system breaks food down.身体的消化系统分解食物。
-
Water can be broken down into hydrogen and oxygen through electrolysis. = Water can break down into hydrogen and oxygen through electrolysis.通过电解作用，水会被分解为氢气和氧气。
b : to be able to be divided or to divide (something) into parts or groups（使）分为 -
The report breaks down into three sections. = The report is broken down into three sections. [=the report has three sections]报告分为三个部分。
-
The author has broken down the nation's history into three distinct periods.作者把这个国家的历史分为三个不同的时期。
4
break (something) down or break down (something) : to use force to push (something) to the ground拆除；捣毁 -
break a door down把门拆除
-
break down a barrier清除障碍
—
sometimes used figuratively有时用作比喻 — see also breakdown