The news spread by word of mouth.

这消息是口头传开的。

《牛津词典》

The story has been passed down by word of mouth.

这个故事是口头流传下来的。

《柯林斯英汉双解大词典》

Word of mouth advertising happens when one person tells another about a good experience with a product or service.

当一个人告诉另一个人对产品或服务的良好体验时，口碑广告就发生了。

youdao

Do not put words in my mouth." Information is often spread through word of mouth.

VOA: special.2010.06.20

So, a lot of it has been word of mouth.

所以很多都是口口相传。

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Word of mouth, even, is a sort of good way to find out.

即使是通过口口相传的信息也可以找到好的实习机会。

多样的实习机会 - SpeakingMax英语口语达人

Besides, this idea of paying people to do word-of-mouth marketing defeats the real intent of word-of-mouth marketing.

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On Wednesday, Nov. 16, I will participate in a panel discussion at the Word-of-Mouth Marketing Association (WOMMA) Summit in Las Vegas to talk about the efficacy of online versus offline word-of-mouth (WOM) marketing campaigns.

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The site probably took an hour to build and from there it snowballed by word-of-mouth, or more correctly word-of-e-mail.

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