不适于呼吸的

例句：

1. 1. The air inside the cave was so thin that it was unbreathable.
   洞穴里的空气质量太稀薄，以至于无法呼吸。
2. 2.The clothes were made of a material that was unbreathable and kept us from breathing properly.
   这些衣服是由一种不透气的材料制成的，让我们无法正常呼吸。
3. 3.The room was filled with smoke, making it unbreathable for anyone to enter.
   房间充满了烟雾，任何人都无法进入。