dissolved oxygen

例句：

1. 1. The fish in the lake is dying because of the low dissolved oxygen levels.
   湖里的鱼因为溶解氧水平低而死亡。
2. 2. The doctor said that the patient needed more oxygen to survive.
   医生说病人需要更多的氧气才能存活。
3. 3. The firefighters were working hard to dissolve the toxic gas in the air.
   消防员们正在努力将空气中的有毒气体溶解掉。