ag是拉丁動詞agere的詞干部分，意思相當于to do或to drive渠驼，意為做或驅(qū)使蜈块。agere的分詞形式為actum, 因此，詞根act與ag同源異形迷扇。
agent= ag- (= to do) + -ent (= person)-> person who does 辦事者->n. person who works for another person or orgnizations 代理人
agency= ag- (= to do) + -ency (= the quality or state) -> the ability or place of doing business 辦事的能力或場所 -> n. power or force which causes a result力量百揭；作用
exact= ex- (= out) + act (= to drive) ->to drive out; driven out 逼出來；逼出來的 -> v. demand or obtain by force蜓席；adj. correct and without mistake 準確的器一；精準的
interact =inter- (= between) + act (= to do) -> to do between two things -> v. have an effect on each other 互相作用，互相影響
