以下三处加粗处，按语法结构剖析，在句子是什么成分？
1. A more imperial policy, dominated by expansionist militarist objectives, generated the tensions that ultimately led to the American Revolution.
2.Freed by warming, waters once locked beneath ice are gnawing at cosplaytal settlements around the Arctic Circle.
3. A push to develop the North, quickened by the melting of the Arctic seas, carries its own rewards and dangers for people in the region.
1 A more imperial policy, dominated by expansionist militarist objectives, generated the tensions that ultimately led to the American Revolution.
过去分词短语是对主语的补充说明，为非限制性定语，等于一个非限制性定语从句：which was dominatedby...。
2.Freed by warming, waters once locked beneath ice are gnawing at coastal settlements around the Arctic Circle.
过去分词短语作缘由状语，修饰谓语动词are gnawiing.
3. A push to develop the North, quickened by the melting of the Arctic seas, carries its own rewards and dangers for people in the region.
名词push在本句的意思为effort。过去分词短语对主语push作补充说明，为非限制性定语，等于一个非限制性定语从句：which has been quickend by...。
