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》

Secure Multipurpose Internet Mail Extensions (S/MIME) allows digital signatures to be attached to e-mail messages, such that the recipient can verify the identity of the signer.

安全多用途 Internet 邮件扩展（Secure Multipurpose Internet Mail Extensions，S/MIME）允许将数字签名附加到电子邮件消息上，这样接收方就可以验证签名者的身份。

youdao

Senator Gramm attached a rider limiting the C.F.T.C. 's authority to an 11, 000-page appropriations bill.

格拉姆参议员将该议案置放于即将通过的拨款法案之中，作为这份长达11 000页议案的一项附加条款。

youdao

Rod puppets are controlled by a stick or wire attached to the puppet's main body parts.

VOA: special.2009.09.23

If it ever did have an author's name attached to it, we don't have any evidence in the manuscript history.

如果它曾经写有作者的名字，那么原始手稿里没有任何证据。

耶鲁公开课 - 新约课程节选

we know that h is always terminal, right after the molecule that it's attached to.

我们知道氢原子永远都在末端，放到和它成键的分子的后面。

麻省理工公开课 - 化学原理课程节选

How some of Nokia's attached cloud services complement or compete with Microsoft's own serious cloud-based initiatives has surely been the subject of many meetings between the two companies, but the apps round out and enhance Nokia's offerings.

ENGADGET: Switched On: Shedding Dead Skins

Groups of long strands of someone else's hair are attached to a client's own hair near the scalp.

NPR: Indian Hair: The Next Hot Beauty Trend?

What's attached to sodium is often the magic-maker, yielding a firmer canned bean or a crispier cracker.

CNN: CookingLight: A 'less is more' approach to sodium