Zhè shì yīgè zhuāngzhòng de chǎnghé, qǐng zhùyì yánxíng.
This is a solemn occasion, please mind your words and behavior.
Tips
usage
庄重 describes a dignified seriousness appropriate for formal occasions. Compare: 严肃 = strict/stern (can be negative), 庄严 = solemn/majestic (grander scale). 庄重 is about personal composure and propriety.
