gelled propellant rocket engine

例句：

1. 1. The gelled propellant rocket engine is a revolutionary technology that could change the way we travel.
   凝胶推进火箭发动机是一种革命性的技术，可能会改变我们旅行的方式。
2. 2. The gelled propellant rocket engine has been used in space exploration for decades.
   凝胶推进火箭发动机在太空探索中已经使用了几十年。
3. 3. The gelled propellant rocket engine is a complex system that requires careful maintenance to ensure its safe operation.
   凝胶推进火箭发动机是一个复杂的系统，需要仔细维护以确保其安全运行。