Meaning of yán sù:
yán sù
严肃
Adjective
(of an atmosphere etc) solemn; grave; serious; (of a manner etc) earnest; severe; exacting
Tā de tàidù fēicháng yánsù.
他的态度非常严肃。
His attitude is very serious.
Tā yòng yī zhǒng fēicháng yánsù de yǔqì jiǎnghuà.
他用一种非常严肃的语气讲话。
He spoke in a very serious tone.
Verb
to strictly enforce
Lǎoshī duì zuòbì wèntí fēicháng yánsù.
老师对作弊问题非常严肃。
The teacher is very strict about the cheating issue.
