likes(bell, sports). likes(mary, music).蕌 likes(mary, sports).H likes(jane, smith).蕌 friend(john, X): -likes(X, reading), likes(X, music friend(john, X): -likes(X, sports), likes(X, music) friend (john, y) 则求解目标为 friend(john, Y 新目标蕌 ikes (x, reading), likes(X, music).Eilikes(bell,sports). likes(mary,music). likes(mary,sports). likes(jane,smith). friend(john,X):-likes(X,reading),likes(X,music). friend(john,X):-likes(X,sports),likes(X,music). ?-friend(john,Y). 则求解目标为 friend(john,Y). 新目标 likes(X,reading),likes(X,music).