huǒ / jiàn / bì / xū / dá / dào / zú / gòu / de / yǔ / zhòu / sù / dù / cái / néng / bǎi / tuō / dì / qiú / yǐn / lì

火箭必须达到足够的宇宙速度，才能摆脱地球引力。

A rocket must reach a sufficient escape velocity to break free from Earth's gravity.