arms

a call to arms

a call to defend or make ready for confrontation

战斗号令

in arms

armed; prepared to fight

武装的；准备战斗的

lay down (one's) arms

cease fighting

停止战斗，投降

take up arms

begin fighting

开始战斗

under arms

equipped and ready for war or battle

处于战备状态的

up in arms (about/over)

protesting vigorously about something

强力反对…

teachers are up in arms about new school tests.

老师们强力反对新的学校测试。