英语-副词He pushed the stick deep into the mud.deep是副词为什么不放在动词前呢

deep作副词,表深入地；在（或至）深处,即Deep in an area means a long way inside it 如They were now deep inside rebel territory。他们现在已深入叛军占领区。。。。deep inside the country。。。深入该国的腹地put sth。deep into表把--深深插入