There's a chemical filter in there that pulls the carbon dioxide out of the breathing gas -- so that, when it comes back to us to breathe again, it's safe to breathe again.
所以在那里面就有个化学过滤器 将二氧化碳从呼吸的气体中去除 这就使我们再次呼吸的时候，能安全地呼吸