The professor walked onto the platform and seated himself in a chair ,( ) for answering
问题描述：
The professor walked onto the platform and seated himself in a chair ,( ) for answering
questions.
A had prepared
B being prepared
C preparing
D prepared
答
我觉得应选D
类似与well prepared（准备充分的）的用法.
相当于（who was）prepared for...做好准备的,愿意的.
前边seated himself in a chair 表示已经坐定了,已经做好准备为大家解答问题了.选prepared更为贴切.而选C preparing 更强调还在准备中.
be prepared for形容已经做好准备了.
prepare for sth.为某事做准备.
不懂追问~说的有道理，但是我觉得不是从句，是形容词作非谓语，对吧是啊。可以直接理解为形容词作定语，也可以理解成省略who/which be的定语从句嘛。定语从句中也常常有who/which be结构省略的现象。这道题主要是区别prepared和preparing表达的含义。