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1·That's why we Chinese talk with each other in Mandrin.

这也是中国人用普通话来相互交流的原因。

2·The invention comprises a handle and a drill bit, wherein the drill bit takes the structure of a trocar and consists of two parts of a sleeve and a mandrin;

本发明包括手柄和钻头，钻头为套管针结构，包括套管和管芯针两部分组成。