Enumeration method: Let A and B be cubic: AAA, AAB, BAA, ABA, ABB, Baa, Bab, BBA, BBB. There are AAB, Baa and ABA in the two up surfaces, which is ***8 times, so it is 3/8.

General algorithm: face up twice, that is, face down once, which is 3 times, and 1 * * * is the third power of 2, which is 3/8.

Remember to adopt when you are satisfied!

Your praise is my motivation.

(* _ _ *) Hee hee ...

I was drinking Coca-Cola in the desert, singing karaoke, riding a lion chasing ants, and answering your questions with a keyboard in my hand! ! !