例句與造句

1. Because of weight constraints, there was no backup retrorocket engine.
2. Astronauts Aldrin had already set foot on the Moon when Luna 15 fired its main retrorocket engine to initiate descent to the surface at 15 : 47 UT on 21 July 1969 . Transmissions ceased four minutes after de-orbit, at a calculated altitude of.
3. It's difficult to find retrorocket engine in a sentence. 用retrorocket engine造句挺難的