He tends to use a lot of slang expressions that I've never heard before.

他往往用许多我以前从未听说过的俚语。

《牛津词典》

A voice she had never heard before, "Sure then I'm here!"

一个她不熟悉的声音传来：“当然，我在这儿！”

youdao

Because young children can make sentences they have never heard before, Chomsky suggested that human infants are born with the ability to learn language.

由于小孩子可以造出他们从未听过的句子，乔姆斯基认为人类婴儿天生就有学习语言的能力。

youdao

She says her kindergarteners from English-speaking families may have never heard Spanish before.

VOA: special.2010.06.17

So, we could create and understand sentences that we never heard before.

因此,我们能够创造和理解,那些我们未曾听过的句子

耶鲁公开课 - 心理学导论课程节选

How would it strike you if you knew nothing about it, if you had never heard of it before, if you open up the covers of this book for the first time?

如果你对新约一无所知，如果你对新约为所未闻，如果这是你，第一次翻开新约，会有什么感觉？

耶鲁公开课 - 新约课程节选

Words I had never heard before had a significance for him, and a private satisfaction.

NEWYORKER: Mr. Bones

He crept to the head of the stairway and heard Obie use a soft and rhythmic voice he had never heard before.

NEWYORKER: Idols

Midway through their set fans were singing along to music they'd never heard before, picking up on the chorus and joining their voices.

WSJ: New player The Lone Bellow storms folk-rock party