spongy boundary condition

例句：

1. 1.The sponge was so soft that it could be molded into any shape.
   海绵非常柔软，可以塑成任何形状。
2. 2. The sponge was used to absorb liquids and oils.
   海绵被用来吸收液体和油。
3. 3.The sponge was used as a cleaning agent for floors and carpets.
   海绵被用作地板和地毯的清洁剂。