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This text made a series of research to Computer Aided Design of the steering clutch in the bulldozer.

本文对推土机中转向离合器计算机辅助设计作了一系列研究。

Quills . It's totally free and since it is a Flash player, the game requires some plug-in to work.

它的完全免费，和因为这是一个Flash Player的游戏需要一些插件在工作。