hole bottom

例句：

1. 1.The hole bottom of the ship is where the cargo is stored.
   船的洞底是货物存放的地方。
2. 2. The engineer carefully inspected the hole bottom before repairing the machine.
   工程师在修理机器之前仔细检查了洞底。
3. 3.The hole bottom of the cave was filled with water.
   洞穴的洞底被水填满了。