n. 间谍；代理人；代理商；特工人员（agent的复数形式）

n an active and efficient cause; capable of producing a certain effect

n a representative who acts on behalf of other persons or organizations

n a substance that exerts some force or effect

n a businessman who buys or sells for another in exchange for a commission

n any agent or representative of a federal agency or bureau

n the semantic role of the animate entity that instigates or causes the happening denoted by the verb in the clause