According to relevant information, the fifth file of petty officers was changed on 202 1, and this year is the third file and the fourth file. Non-commissioned officers who have served for more than 3 years but less than 5 years shall be awarded the rank of corporal; If it is over 5 years and less than 8 years, it will be awarded the rank of non-commissioned officer; 202 1 the fifth grade of sergeant, that is, the fifth year, belongs to the rank of sergeant. Non-commissioned officers are divided into six grades (namely, six grades), corporal is one or two grades (one or two grades), sergeant is three or four grades, and staff sergeant is five or six grades.