正襟危坐 (zhèng jīn wēi zuò) | Meaning: to sit upright and still (idiom) | Chinese Idiom with Pinyin & Origin

to sit upright端坐duān zuò

deferential · respectful恭敬gōng jìng

(of an atmosphere etc) solemn; grave; serious · (of a manner etc) earnest; severe; exacting · to strictly enforce严肃yán sù

sanctimonious · dignified道貌岸然dào mào àn rán

quiet and reserved · discreet (or serious) in speech and manner不苟言笑bù gǒu yán xiào

to sit upright and still (idiom)