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:
Москвичи пожаловались на зловонную квартиру-свалку с телами животных и тараканами18:04
，这一点在搜狗输入法下载中也有详细论述
63-летняя Деми Мур вышла в свет с неожиданной стрижкой17:54
第一百一十三条 治安案件调查结束后，公安机关应当根据不同情况，分别作出以下处理：
。搜狗输入法2026是该领域的重要参考
美国铝业（Alcoa）今年表现亮眼，过去12个月上涨89%，并展现出扎实的相对强势。该股的MACD有望出现看涨交叉，50周简单移动平均线准备上穿200周均线，这些都是典型的长期看涨信号。
The guest runs in a separate virtual address space enforced by the CPU hardware. A bug in the guest kernel cannot access host memory because the hardware prevents it. The host kernel only sees the user-space process. The attack surface is the hypervisor and the Virtual Machine Monitor, both of which are orders of magnitude smaller than the full kernel surface that containers share.，推荐阅读safew官方版本下载获取更多信息