千米

qiān mǐ bō fú shè

千米波辐射

kilometre wave radiation

tā fēi xíng sù dù huǎn màn zài wú fēng huán jìng xia shí sù zhǐ yǒu qiān mǐ

它飞行速度缓慢，在无风环境下时速只有7千米。

It will fly slowly, only at about 7kph in windless conditions.