Hello, I'm glad to answer your question. I am an old student of 16 senior three. Let me answer this question: (CUA) ∩ (CUB) = CU (A ∪ B) (CUA): refers to the complement of A in the complete set U; ∩: indicates intersection; Complement set A and B in the complete set U intersect, and after the complement set U in the complete set U is equal to A and B, the complement set U in the complete set U. You can't understand the formula C U (A ∪ B) = C U A ∪ C U B, so I suggest you draw a picture first.