That is, there are eight situations.
1: C first, B first, D later.
2: C first, B first, C third.
3: C first, D fourth, D second.
4: C first, D fourth, C third.
5: A comes second, B comes first and D comes second.
6: A comes second, B comes first and C comes third.
7: A second, D fourth, D second.
8: A is second, D is fourth and C is third.
Obviously, the contradiction of 1, 2, 3, 4, 5 and 7 is the same statement.
That is, the first place is _ B, the second is A _, the third is _ _ C _, and the fourth is _ _ D _.