Subject + 严肃 + 地 + Verb
The adjective 严肃 (yánsù) means "serious," "solemn," or "stern," describing a grave or earnest manner or tone. It is used to characterize people's expressions, attitudes, or the tone of a situation. It often appears with 地 as an adverb: 严肃地 (seriously).
老师严肃地说:"这件事必须认真对待。"
lǎoshī yánsù de shuō: "zhè jiàn shì bìxū rènzhēn duìdài."
The teacher said seriously, "This matter must be taken seriously."
他平时爱开玩笑,但今天表情很严肃。
tā píngshí ài kāi wánxiào, dàn jīntiān biǎoqíng hěn yánsù.
He usually likes to joke around, but today his expression was very serious.
会议的气氛突然变得严肃起来。
huìyì de qìfēn tūrán biàn de yánsù qǐlái.
The atmosphere of the meeting suddenly became serious.