在一些国家，服兵役是强制性的。

Military ___service is mandatory in some countries.

他于1964年加入空军，并在部队服役了十年。

He joined the air force in 1964 and spent ten years in the ___service.

他完成了兵役，现在正在回家的路上。

He finished his military ___service, and now he was on his way to his family.