These aircraft are still earning their keep.

【earn】这些飞机还值得使用。

Some rules separating words really are critical—but they must earn their keep.

有些分隔单词的规则确实很关键——但它们必须得到遵守。

Being much further along the road in earning their keep, these delivery bots are helping to pave the way for the time when bigger autonomous vehicles can join them.

这些送货机器人在赚取收入方面走得更远，正在帮助为更大的自动驾驶汽车加入它们的时代铺平道路。