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 is a truly delightful place, which looks the same as it must have done 100 years ago with its winding streets and pretty cottages.

这真是一个令人愉快的地方，它一百年前一定和现在看起来一样，有蜿蜒的街道和漂亮的小屋。

youdao

The message string (MSGSTR) is the string as it must appear in the target language.

消息字符串(msgstr)是必须用目标语言显示的字符串。

youdao

The experts also say you must look at the picture as the American public saw it in nineteen forty-five.

VOA: special.2010.05.31

At any rate, the reader must regard it as creative writing rather than simply a record of life."

无论从哪一层面来看，把它当作是极具创想的作品,而不单单是生活的记录“

耶鲁公开课 - 1945年后的美国小说课程节选

The possibilities of freedom must always, in their view, be balanced with the world as it as--not as it ought to be.

在他们看来,自由的存在可能性,必须与现实相结合,而不是理所当然的

耶鲁公开课 - 美国内战与重建课程节选

That was news to me as it must have been to Mrs Miller and her family.

BBC: New "Welsh" name tipped for Secretary of State's job

Uncomfortable as it must have been, it was a situation Grant was used to dealing with.

BBC: Grant's chance to silence doubters

China's own growth is slowing, as it must if inflation is to be checked.

ECONOMIST: Leaders