Definition
If an emotion is written all over someone's face, it means that their feeling is very obvious and easily perceived by others.
（情绪）清楚地表现在某人的脸上
Surprise was written all over his face when he saw me; his mouth dropped open.
当他看到我时，惊讶之情写满了他脸；他的嘴巴张得大大的。
She tried to hide her disappointment, but her frustration was written all over her face.
她试图掩饰自己的失望，但她的沮丧之情写满了她的脸。
Joy was written all over his face when he heard about his promotion.
当他听到自己升职的消息时，喜悦之情写满了他的脸。