toxic agent

例句：

1. 1. The chemical was found to be highly toxic and should not be inhaled.
   这种化学物质被发现具有高度毒性，不应该吸入。
2. 2. The poisonous snake had already bitten the man before he could escape.
   那条有毒的蛇在那人逃跑之前已经咬了他。
3. 3. The toxic agent was responsible for the outbreak of the disease.
   这种有毒物质是疾病爆发的原因。