At present, the launch of satellite, space shuttle and airship is based on the power which is produced by rocket.It is expensive and not safe.Moreover, it cannot produce thrust powerful enough.是什么意思_At present, the launch of satellite, space shuttle and airship is based on the power which is produced by rocket.It is expensive and not safe.Moreover, it cannot produce thrust powerful enough.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句