奇怪的四级英语句子~“But those captured were anything but terrorists,m

这终语法现象称作独立主格结构,其结构是“主格 + 补足语”.这种结构是用来作状语的,其语法功能与分词短语作状语基本相同,只不过分词短语可以用作时间、原因、条件和伴随方式状语,而其他形式的独立主格一般只表示伴随方式.
1.关于独立主格
由于该结构是用来作主要句子的附加成分的,但是补足语却与句子的主语没有关系,而是与另加的“主格（名词或代词）”是密不可分的,因为这个主格独立于句子的主语而存在,因此称作独立主格,其中代表主格的名词或代词是其后补足语的逻辑主语.
2.关于补足语
独立主格结构中补足语可以由下列词语充当：
* 分词短语,如：
He made a speech at the meeting,the others paying no attention to what he was saying.他在会上发言,其他人每人注意他正在说什么.
（= He made a speech at the meeting,while the others paid no attention to what he wan saying）
* 形容词短语,如：
We looked down the hill,the trees green everywhere.我们向山下看去,树木一片郁郁葱葱.
（= We looked down the hill and the trees were green everywhere.）
* 介词短语,如：
The woman came in,a dog after her.那个女人走了进来,身后跟了一只狗.
（The woman came in and a dog was after her.）
* 名词短语,如本题：
Those captured were anything but terrorists,most of them illegal immigrants from Central or South America.那些被抓捕的人根本就不是什么恐怖分子,他们大多数是来自中部地区或南美洲的非法移民.年
（= ...and most of them were illegal immigrants from Central or South America.）