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:
党中央决定，在全党开展树立和践行正确政绩观学习教育。习近平总书记反复强调要树立和践行正确政绩观，近期又在多次重要讲话中特别加以强调，为开展学习教育指明了方向、提供了重要遵循。
。业内人士推荐51吃瓜作为进阶阅读
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