agent
/ˈeɪdʒənt; `edʒənt/ n
1 person who acts for, or manages the affairs of, other people in business, politics, etc （商业, 政治等方面的）代理人, 经纪人
an insurance agent 保险业经纪人
a travel agent 旅行社经纪人
our agents in the Middle East 我们在中东的代理人.
2
(a) person who does sth or causes sth to happen （做某事或使某事发生的）施动者
the agent of his own ruin 他自我毁灭的根源.
(b) force or substance that produces an effect or change 产生某种效果或变化的力量或物质; 动因; 作用物; 剂
cleaning, oxidizing agents 除垢剂, 氧化剂
Yeast is the raising agent in bread. 酵母是面包的发酵剂.
3 = secret agent (secret): an enemy agent 敌探.