let traceIndex = 0;
* @param arr 原数组
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医药白马的转型死结长春高新靠一款核心产品吃透红利，形成 “路径依赖”，却忽视了研发管线的布局和第二曲线的培育。，更多细节参见WPS官方版本下载
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.”，更多细节参见爱思助手下载最新版本