汤放太久，现在已经冰凉了。

The soup has been left too long and is now ___stone-cold.

无论我怎么道歉，她都表现得无动于衷。

No matter how I apologized, she remained ___stone-cold.

他的不在场证明是铁证如山，完全无法反驳。

His alibi was ___stone-cold, making it impossible to challenge.