An absolute phrase combines a noun and a participle with any accompanying modifiers or objects
1) Legs quivering
Legs = noun; quivering = participle.
2) Her arms folded across her chest
Arms = noun; folded = participle; her, across her chest = modifiers.
3) Her work completed, Amanda flew home.
[noun work + participle completed]
4) We scrambled along the shore, the waves splashing at our feet.
[noun waves + participle splashing]
5) The audience filed out, some to return home, others to gather at the pub.
[pronoun some + infinitive to return; pronoun others + infinitive to gather]