Adverb:

1. under the feet;

   "trampled the beans underfoot"
   "green grass growing underfoot"
   

2. in the way and hindering progress;

   "a house with children and pets and toys always underfoot"
   

downadv.向下prep.沿着 ... 而下adj.向下的；消沉的；无礼的n.绒毛；汗毛v.击倒；打败；吞下；被抑制

undergroundadj.地下的；秘密的adv.在地下；秘密地n.地下；地铁；地道；秘密活动

1. The snow underfoot was soft and deep.
   脚下的雪又软又厚。
2. Fallen riders were trampled underfoot by the charging horses.
   摔下来的骑手遭飞奔马群践踏。
3. Her three children are always getting underfoot.
   她的三个孩子老是碍手碍脚。