fatal concentration

例句：

1. 1.The toxic gases in the factory are at a fatal concentration.
   工厂里的有毒气体浓度很高。
2. 2. The scientist carefully measured the fatal concentration of the poison.
   科学家小心翼翼地测量了这种毒药的致命浓度。
3. 3. The firefighters were working to reduce the fatal concentration of carbon monoxide.
   消防员们正在努力降低一氧化碳的致命浓度。