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:
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，更多细节参见夫子
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值得注意的是，针对此前备受用户吐槽的「微信文件重复保存吃内存」问题，微信官方此次也借机作出了明确回应：
Совсем озверелиКрокодилы, кабаны и обезьяны объявили войну людям. Никто не знает, как их остановить29 декабря 2019