他的承诺坚如磐石，从不食言。

His promise is ___rock-solid, he never breaks his word.

这座桥的混凝土结构非常坚固，经过多次地震都完好无损。

The bridge's concrete structure is ___rock-solid, surviving multiple earthquakes without damage.

尽管面临挑战，他依然保持着坚定的信念。

Despite the challenges, his faith remained ___rock-solid.