attention有立正的意思，但也可以call people to listen to an announcement, etc:

"Attention, please. Could Passenger Ross Geller please proceed to Gate 25 immediately."

military command: 军事口令

fall in: take one's place in a military formation or line

squad-shun: 按班立正。shun: order soldiers to come to attention

(stand) at ease: used to tell soldiers to stand in a relaxed way with their feet apart

stand easy: stand with more freedom of movement than when at ease

Military Customs and Courtesies... Rendering The Hand Salute

When on campus and in uniform [制服], cadets [军校生] will salute [敬礼] all cadet officers and cadre [*] officers of all services. It is appropriate to accompany the salute with a word of greeting, for example, "Good morning, sir." "Sir, Cadet Jones reports."

When an officer approaches a uniformed group outside, the first cadet to recognize the officer will call "Attention" and all cadets will salute and remain at attention until given "At ease", "Rest", "Carry on", another command, or until the officer passes.