1. 释义：激烈的；残酷无情的；不择手段的

2.同义替换： fierce= tough= severe= relentless

3. 例句：

就像很多在线商业一样，打车行业的竞争是冷酷无情的，赢者通吃的市场：滴滴本身就是2015年两个本地公司合并的产物。

Ride-hailing, like many online businesses, is a cut-throat, winner-takes-all market: Didi itself is the product of a 2015 merger of two local firms.

4. 造句：

在这个竞争激烈的世界，只有适者才能生存。 

In this world full of cut-throat competition, only the fittest can survive.

参考： In this cut-throat world, only the fittest will survive/prevail.

新闻行业的竞争会相当残酷。

The journalism can be a very cut-throat business.