The great majority of people are in favour of this change中文释义是"绝大多数人赞成这一变化"能否把句子简化成"The great majority of people are favour this change",如若不能,为什么?

因为 are 后面必须是形容词 而这里 的favour 是名词
你可以改成
The great majority of people are favourable of this change

不完全同意 1 楼说法.are 后面不一定必须是形容词,也可以跟名词,比如：
"The great majority of people are students."
但这句话,我认为 "in favor of"是一个特定词组,必须如此用.
favor 是名词,也可用作动词,所以另一种通常的说法是：
The great majority of people favor this change.
（注：favor = favour,本人习惯美式拼法.）