①Crises in international diplomacy do not always result from malice; for nations, like individuals, can find themselves locked into difficult positions, unable to back down.

请问老师，unable to back down，形容词作状语吗？修饰locked？

【答】unable to back down，是形容词短语作状语，具体说是“结果状语”，修饰前文整个谓语部分。其逻辑主语自然是句子的主语 nations。

②For the first time in the modern era, non-Hispanic Whites are officially a minority in California, amounting to a little less than half the population of the state, down from nearly three-quarters a decade ago.

down是什么词性呢？down from这里是做定语修饰population吧？

【答】down 是副词，down from nearly three-quarters a decade ago 是介词的短语，其作用是解释上文 a little less than half the population of the state 这个说法的。在意思上，是其同位语。“略低于该州人口的一半 = 低于10年前的近四分之三”。它们之间是相等关系。

③Paleontologist Stephen Jay Gould has argued that many biological traits are not the products of natural selection, favored because they enhance reproduction or survival, but are simply random by-products of other evolutionary developments.

请问老师，favored 做状语还是定语？

【答】整个favored because they enhance reproduction or survival, but are simply random by-products of other evolutionary developments，这一部分是the products of natural selection 的非限制性定语，本身又含有一个原因从句。相当于...the products of natural selection, which are favored because...

可以这样翻译：“这些自然选择的产物受宠的原因是...”。