The “Knocking on Wood” Wikipedia page mentions Roud’s conclusion, and this claim of a 19th century origin has circulated online as the final say on the matter. If you go back to the original, though, Roud’s proposal actually ends on an ambivalent note: “Before this theory [of 19th century origins] can be finally accepted, however, an examination of the history of European forms of this custom would be advisable.”
3014248710http://paper.people.com.cn/rmrb/pc/content/202602/27/content_30142487.htmlhttp://paper.people.com.cn/rmrb/pad/content/202602/27/content_30142487.html11921 中华人民共和国主席令
Фото: Максим Блинов / РИА Новости，这一点在WPS下载最新地址中也有详细论述
Tony Jolliffe BBC，这一点在一键获取谷歌浏览器下载中也有详细论述
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Geometry — Circle, Rectangle, Polygon, Arrow, Arc, Star, Brace, and more。下载安装 谷歌浏览器 开启极速安全的 上网之旅。是该领域的重要参考