excavator n. 挖掘机

例句：In soft clay, tubes of the extending type can easily be pushed down through the clay by using a mechanical excavator.
在软泥中，可以利用挖掘机，很容易地把需要延伸的管子穿过泥土推下去。

excavate v. 挖掘

例句：All trace of properly laid-out burial grounds is lacking, probably because the earliest strata are below water level and it has so far been impossible to excavate them.
也许是因为最初的地面在水平面以下，我们已没法挖掘埋藏在地下的印度河文明城市的最初踪迹。