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.”
他给出的原因是：“一是针对老年人高质量的数据语料库建立是脏活苦活儿；二是对创业团队的技术、运营、市场的理解要求度更高。”。业内人士推荐谷歌浏览器【最新下载地址】作为进阶阅读
https://www.washingtonpost.com/technology/2026/01/27/anthropic-ai-scan-destroy-books/。WPS官方版本下载是该领域的重要参考
"message": "Amount must be non-zero."