The plural 's' is not a free form, as it must always be attached to a noun.

表示复数的s不是自由语素，必须附着于名词。

《牛津词典》

In such cases, the program manager and (ultimately) the executive sponsor (s) must represent the program and make decisions on its behalf.

在这种情况下，规划经理和(最终)高层执行官(们)必须代表他们自身对规划提出异议或作出决策。

youdao

The application(s) must integrate fully into the backend system(s), regardless of device type or platform.

应用程序必须完全集成到后端系统中，不论是什么设备类型或平台。

youdao

This young man must struggle between his moral beliefs and his desire to seek punishment for his father's death.

VOA: special.2010.01.06

So, it's rather unique for the Westside, Los Angeles and for the world, I must say.

我必须得说，这对于西区、洛杉矶和整个世界都很特别。

关于肌肉海滩 - SpeakingMax英语口语达人

But it's a good story, Joule decided that there must be a direct relationship between work and heat.

所以说，这只是一个不错的故事而已，焦耳认为功和热之间,一定具有某种直接的联系。

麻省理工公开课 - 热力学与动力学课程节选

Just as Facebook's users must come to grips with the fact that they can longer reach all their friends with an update unless they pay for "promotion, " Instagram's users must reconcile themselves to the fact that their photographic creations are now grist for some advertiser's mill.

CNN: Instagram users should wise up

If they then show enough additional Gore votes to overturn Mr Bush's lead, she must give Florida's 25 electoral votes to Mr Gore and with it the presidency.

ECONOMIST: Whatever will they think of next?

If the youths warm to each other, the fair can trigger complex financial negotiations about the price a young man's family must pay to a woman's parents if they are to wed.

NPR: Gypsies Flock To Bridal Fair As Parents Negotiate