This is called "shouting password". Not only soldiers, but also physical education class and runners always use short passwords to keep pace.

And "exercise, body! Defend the motherland! " .

In some countries, the pronunciation of numbers is quite lengthy. Shout four simple letters when running.

Our Chinese expression of numbers is very simple, so it is very convenient to use it to run and shout slogans. So it's used more there.

Morning exercises for the graduating class can also be called "Work hard and study hard! Take a good exam and get good grades! 》