lethal concentration

例句：

1. 1. The chemical was found to be extremely toxic at the lethal concentration.
   该化学物质被发现在极高毒性下。
2. 2. The research team conducted tests to determine the lethal concentration of the poisonous gas.
   研究团队进行了测试，以确定有毒气体的致命浓度。
3. 3. In a laboratory experiment, we tested the lethal concentration of the acid on human skin.
   在一个实验室实验中，我们测试了这种酸对人皮肤的致命浓度。