on edge ----> nervous // angry
on her own ----> herself
on purpose ----> intentionally
on sale ----> cheap
on the dot ----> on time // punctual
one step at a time ----> gradually
out of earshot ----> too far away to hear
out of one's mind ----> crazy // foolish idea
out of order ----> not working right
outcome ----> decision
outgoing ----> friendly
over one's head ----> not understand
overreact ----> too sensitive
责任编辑：虫虫
