肃静

例句：

1. 1.The room was so quiet that I could hear the sound of my own breathing.
   房间非常安静，我几乎能听到自己的呼吸声。
2. 2.The teacher walked into the classroom with a serious expression, making everyone feel very solemn.
   老师带着严肃的表情走进教室，让每个人都感到非常庄重。
3. 3. The old man sat in his chair, looking at the bookshelves with a solemn expression, as if he was contemplating something profound.
   老人坐在椅子上，看着书架，脸上表情严肃，仿佛在深思着什么深奥的东西。