第三十二条 任何个人和组织不得未经互联网服务提供者授权，开发、销售、提供附加于其服务并影响服务正常运行或者损害用户公平交易的客户端软件或者服务平台。
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.”
。搜狗输入法下载对此有专业解读
Hit "Run" to watch particles bounce around with quadtree-accelerated collision detection:，更多细节参见WPS官方版本下载
What has the National Screening Committee recommended?。业内人士推荐爱思助手下载最新版本作为进阶阅读