They plan to excavate a large hole before putting in the foundations.他们计划打地基前先挖个大洞。A contractor was hired to drain the reservoir and to excavate soil from one area for replacement with clay.雇了一个承包商把水库抽干，挖掉一处的泥土，然后再用黏土填充。It will not be necessary to excavate the tooth thoroughly.不需要把这颗牙齿全部掏空。