What does it mean to be plain?

It's wrong to speak lightly. It's strange to speak.

Tan T ǔ Bangbang's Talk: Levels, Features and Styles of Speech in Daily Life. Based on a certain language, people's ideological and cultural level, education and interest, and the reflection of speech and behavior are all important basis for people to form an evaluation of a person. Extraordinary: unusual; Outstanding; Extraordinary speech means that what you say has a certain level and is more recognizable than others. In modern and ancient times, they are mostly used to praise the wonderful speeches of scholars and critics.

Part of speech: commendatory term