solid

一旦冷却，熔化的玻璃就会变成固体。

Once cooled, the molten glass becomes ___solid.

这条小路不再是泥泞的，而是坚实的地面。

The path was no longer muddy but ___solid ground.

液体和固体废物被收集在罐子里。

Liquid and ___solid waste is collected in the tank.