不知轻重

lit. not knowing what's important (idiom); no appreciation of the gravity of things / naive / doesn't know who's who / no sense of priorities

no; not so / (bound form) not; un-

not to know / unaware / unknowingly / fig. not to admit (defeat, hardships, tiredness etc)

to know / to be aware

light / easy / gentle / soft / reckless / unimportant / frivolous / small in number / unstressed / neutral / to disparage

severity (of the case) / degree of seriousness / whether sth is slight or serious

to repeat / repetition / again / re- / classifier: layer

heavy / serious / to attach importance to