There are four friends: A, B, C and D  They are musicians, scientists, astronomers and logicians  When they were young, they used to predict the future together  At that time, a predicted that I could not become a scientist anyway  B predicted that C would be a logician in the future  C predicted that D would not become a musician  D predicted that B could not become an astronomer
In fact, Only the logician predicted correctly
A is a logician, B is an astronomer, C is a scientist, and D is a musician.