third rocket stage

• 第三级火箭

third rocket stage的用法和样例：

例句

1. As the first rocket burns out, the second-stage motor ignites.
   当第一级火箭燃料烧尽时，第二级火箭的发动机就点燃了。
2. As the step rocket goes up,some of the stages at the side fall away.
   当多级火箭上升时，边上的几级火箭就脱落了。