OG2017阅读长难句求解

小炎炎

Many fairly common amphibian species declared all but extinct after severe declines in the 1950s and 1960s have subsequently recovered, and so might the apparently declining populations that have generated the current appearance of an amphibian crisis.

这个句子的意思我大概懂，就是以前被宣告灭绝的那些动物后来又恢复数量了，现在这些数量下降的动物也会恢复数量

我的问题是
declared all but那个地方是什么意思？这是个什么结构？我读不太明白

远飞翔

有一点， declared all but extinct 过去分词结构 形容词性修饰species 表被动，而不是which省略结构，gmat里which不能这样用，也不可以这样省略。

小炎炎

咖啡印象 发表于 2017-4-19 11:07
Many fairly common amphibian species (which are) declared all but extinct after severe declines in t ...

好的，谢谢

咖啡印象

Many fairly common amphibian species (which are) declared all but extinct after severe declines in the 1950s and 1960s have subsequently recovered...

all but extinct是“几乎灭绝”的意思，参见一个栗子：

Once a common species in Britain, ospreys were all but extinct by 1916, but their numbers have since increased thanks to conservation efforts.