1. zero in on

Meaning: If you zero in on something, you focus your attention on it.
中文解析：瞄準，對準…；對…集中火力、注意力

If you're reporting on an issue rather than an event, first get the reader interested by zeroing in on the main players and their conflict.
如果你在就某爭議問題做報告而非某事件，那么首先你要讓讀者注意到主角和他們之間的沖突。

I like the way our lecturer zeroes in on the central issues without spending too much time on all that boring background information.
我喜歡這種授課風格，授課者直接集中火力在主要事件上而非花過多時間在無聊的背景信息上。

2. zero tolerance

Meaning: If something is given zero tolerance, it won't be accepted even once.
中文解析：零容忍，一次都不允許。

Because of the school's zero-tolerance policy, our boy was expelled for smoking just one cigarette.
由于學校采取零容忍政策，所以學校男生僅僅因為吸了一根煙就被開除了。

3. zero-sum game

Meaning: A zero-sum game is a situation in which any gain by one side or person is at the expense of a loss to another side or person involved in the situation.
中文解析：零和博弈又稱零和游戲(zero-sum game)，與非零和博弈相對，是博弈論的一個概念，屬非合作博弈，指參與博弈的各方，在嚴格競爭下，一方的收益必然意味著另一方的損失，博弈各方的收益和損失相加總和永遠為“零”。雙方不存在合作的可能。

The stock market has become a giant zero-sum game in which one investor gains what another investor loses.
股票市場已經成了一個巨大的零和博弈游戲，在股票市場中一個投資者賺到的同時就會有另一個投資者輸錢。

In a zero-sun game, if you add the total gains of the participants and the total losses of the participants, the sum will always be zero.
在零和游戲中，如果你把所有參與者賺到的和輸掉的加在一起，總和永遠是零。

（來源：滬江英語，編輯 Helen）