Outside the orb's metallic skeletal frame is darkness.

在球体的金属骨架外，是一片黑暗。

For example, the introduction of iron and steel skeletal frames made thick, load-bearing walls unnecessary, expanding the usable square footage of buildings and increasing the use of windows and availability of natural light.

例如，钢铁骨架的引入使得厚实的承重墙变得不必要，扩大了建筑物的可用面积， 增加了窗户的使用和自然光的可用性。