.4、工程机械概述 As we look around us we see a world full of “things”: machines, devices, tools; things that we have designed, built, and used; things made of wood, metals, ceramics, and plastics. We know from experience that some things are better than others; they last longer, cost less, are quieter, look better, or are easier to use. 正如我们环顾四周我们看到世界的“东西”机器全设备工具;事情我们已经设计建造和使用;木材金属陶瓷制成的东西和塑料。我们从经验知道有些事情是比别人做得更好他们去年更长成本更低更安静看起来更好或者更容易使用。理想的情况. Ideally, ho
