Altogether there are some ten thousand of these volcanoes on Earth,all but a few hundred of them extinct.
1) extinct本身为形容词,这里在句子中是什么成分?属于什么用法。
2)all but a few 是什么意思?
1】 整个后半句是独立主格用法,即“名词/代词+形容词”
2】all but指除了but后面提到的以外,所有的。是一个短语,字典都有收录。如All but one of the plates were damaged.除去一只,盘子全打碎了。而a few是修饰hundred的,表示数百个。所以不是你理解的all but a few这种搭配。