A talk on American culture was given in the school hall yest

啊哈,这里要用被动语态其实原因很简单,因为[演讲]不是[人],不能做出动作.
演讲是被人演讲的.( 好别扭的中文)
也就是,A talk (spoken) by somebody was given in the school 或 Somebody gave a talk in the school.
至于书上说的动宾关系指的是谓语动词give 和宾语 talk是配对关系,也就是give a talk,
因为是被动式,这里的a talk其实是give的宾语.
说的有点啰嗦希望没把你搞晕 ; )