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》

It? S not a formal specification, but a readable introduction to each language feature.

它并不是一个标准规范，而是一本介绍每门语言特性的可读书籍。

youdao

It managers: The first time someone does something wrong, it \ \ \ 's not a mistake — it \ \ \' s a learning experience.

IT经理：如果有人第一次做错了事情，这不是犯错误，而是学习所需要代价。

youdao

Washington,D.C. is the country's capital but it is a city,not a state, so it does not have its own star.

VOA: special.2010.04.02

It's not a social role in the way that she could be granddaughterly or motherly on those other occasions.

这不是一个她可以像孙女,或者母亲一样的社会角色。

耶鲁公开课 - 1945年后的美国小说课程节选

Opponents of animal testing are quick to point out that it's not a humane way to learn scientific facts.

动物实验的反对者很快就指出，利用这种方法得到科学事实是不人道的。

需要动物实验吗？ - SpeakingMax英语口语达人

We are not stepping out and saying it's a hit or it's not a hit.

NPR: 2 With Gang Ties Sought In Colo. Prison Boss Death

Question: So if you say it's not a gift, it's not a gift?

NPR: Defense, Prosecution Rest In Sen. Stevens' Trial

Mr. STORM: So it's not a, you know, it's not the Maharishi, and it's the typical - it's not a bio show by any means.

NPR: Cirque du Soleil Interprets the Fab Four