invincible

他相信自己无敌于天下。

He believes he is ___invincible in the world.

超级英雄在电影中总是看起来无敌。

Superheroes in movies always seem ___invincible.

面对挑战，他保持着不可战胜的乐观态度。

Facing challenges, he maintains an ___invincible optimism.