坚不可摧用英语怎么说？

坚不可摧

例句

• The lofty walls of the castle seemed impregnable. 这座城堡的高墙似乎坚不可摧。
• They will establish impregnable fortresses. 他们将建造坚不可摧的城堡.
• His opponents were still obsessed by his seeming invulnerability. 他的对手还仍然对他表面上的坚不可摧感到棘手.