They switched from set speeches to a question-and-answer format.是什么意思？

They switched from set speeches to a question-and-answer format.

他们从事先准备好讲稿的演说转向一问一答的形式。

they

pron. 他/她/它们，人们，大家，政府，当局，她们；

例句
The storms had abated by the time they rounded Cape Horn.
他们绕过合恩角时，暴风雨已经减弱。

switched

v. 转变，改变( switch的过去式和过去分词 )，转换，挥动（棍棒、鞭子等），迅速转动；

例句
The workforce have recently been calling for their working hours to be reduced. Many companies have accordingly switched to a five-day week.
工人们最近一直在呼吁缩短工作时间。许多公司于是转成了一周五天工作制。

from

prep. （表示时间）从…，（表示原因）因为，（表示来源）来自…，（表示分离）与…分离[隔开]；

例句
...an abortive attempt to prevent the current President from taking office.
企图阻止现任总统连任的失败尝试

set

vt. 放置，安置，使处于某种状况，设置，摆放餐具；vi. 落山，出发，凝结；n. 一套，一副，集合，布景，电视机；adj. 固定的，位于…的，顽固的，安排好的；

例句
Shops, houses, and vehicles were set ablaze.
店铺、房子和车辆全都陷于火海。

speeches

n. 说话( speech的名词复数 )，演说，说话方式，口语；

例句
The opening speeches sounded more like declarations of war than offerings of peace.
开场的几段讲话听上去更像是战争宣言而不是和平倡议。

to

prep. 向，朝着，到，关于，属于；adv. 朝一个方向的，到某种状态，关闭；

例句
I suggest you leave it to an expert...
我建议你把它留给专家来解决。

format

n. （出版物的）版式，[自]（数据安排的）形式，电视节目的总安排（或计划）；vt. 使格式化，安排…的格局，设计…的版面；vi. 设计一个版式；

例句
I had met with him to explain the format of the programme and what we had in mind.
我已经和他当面解释了我们节目的形式以及我们的想法。