Mr. S, Mr. P and Mr. Q know that there are 16 playing cards in the desk drawer: hearts A, Q, spades J, 8, 4, 2, 7,

2, 3, 4, 7, 8, J of spades.

Cao Hua 4, 5, 6, Q, K

Square a, 5

P knows the number of points and q knows the color.

PQ can't tell which card it is, which means it has the same confused choice, or the same suit (this is obvious) or the same number of points (this is very important). A (two reds), 4 (two blacks and one red), 5 (black red) and Q (black red) with the same number of points. P I don't know, which means that card must be in these cards. It's important that Q knows P doesn't know this sentence. Q why do you know? Why did you say that? Everyone knows what card it is. In addition, it should be noted that the cards drawn are unique and certain. So, starting from reasoning, Q's words to P imply that on the one hand, it is a heavy truck, but on the other hand, what about P? P doesn't know what the color of the cards Q sees, let alone the specific color, so it seems that every heavy card is possible, but it doesn't seem to be, which is why Q knows. P can guess any one except four hearts. Q's suggestion denies the black of the three, and red heart four is the only definite choice of P.