What does Duke Zhou mean by dreaming that the classroom is clean?

There are two meanings, you should judge according to the actual situation: first, there were cumbersome things in the past, but now they have been solved. Second, there have been complicated things that I want to solve but I haven't solved well. I think you may be the second case, otherwise you wouldn't have this dream. "classroom" symbolizes your state of mind, which may be the state of mind of learning "I cleaned", indicating that only when it is unclean will it be cleaned, and it will be clean when it is cleaned. Here is the meaning of actively solving problems. In reality, you may be doing some kind of study, but you have one thing bothering you, and you want to get rid of it quickly, so you have this dream.