这座城堡有一座华丽的螺旋楼梯。

The castle featured an ornate spiral ___staircase.

他们在房子后面加装了一个坚固的室外楼梯。

They added a sturdy outside ___staircase to the back of the house.

停电期间，我们不得不使用紧急楼梯。

During the power outage, we had to use the emergency ___staircase.