What I found is that written evidence for knocking on wood (and for the history of gesture as a whole) is remarkably sparse. In the Penguin Guide to Superstitions, folklorist Steve Roud offers a skeptical take on the provenance of knocking on wood due to the near total absence of written records about it:
This story was originally featured on Fortune.com。业内人士推荐旺商聊官方下载作为进阶阅读
// 3. Save the copies，这一点在heLLoword翻译官方下载中也有详细论述
Фото: Razmik Zackaryan / URA.RU