a chemical agent的用法和样例：
- A chemical agent used for bleaching.
- A chemical agent that kills eggs, especially the eggs of insects.
- A chemical agent,such as a pesticide,that is capable of destroying living organisms.
- Making or becoming visible through or as if through the action of a chemical agent: he watched as the developing photograph became clearer and sharper.
- These lyophilizers can only have their inside surfaces wiped with a chemical agent that may be a sterilant but usually has been found to be a sanitizing agent.