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:
FT Professional
。业内人士推荐爱思助手下载最新版本作为进阶阅读
"It could be a way to make those professions way more attractive and get the productivity back up."
8、DataWorks整库同步解决方案
12月21日,北京海淀大悦城正式开业。新京报记者 浦峰 摄