服兵役；服劳役to be in active service; to enlist in the army; to do corvée labour(Britain); to do corvée labor(US)

• 服役年龄

  military age

• 在军队里服役

  serve in the armed forces

• 你服役几年了？

  how many years did you serve?

• 延长服役期限

  extend a length of service

• 缩短服役期限

  shorten a length of service