因为早期的地球大气中缺乏氧气，所以也缺乏起保护作用的臭氧层屏障。
Because early Earth lacked oxygen in its atmosphere, it also lacked a protective ozone barrier.
表层是百叶窗、起保护作用的厚壁和微裂缝，这些都能突出建筑主题。
The blind facade, the protective thick wall, and the slight crevices, all these above reinforce the architectural theme.
在眼睛最外层起保护作用的薄膜是角膜。光线通过这层薄膜后，就进入了虹膜。
The protective bit at the front of the eye is the cornea and once light passes through this membrane, it passes through the iris.
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