Solution: Suppose the first sentence said by the first teacher is correct, C is the first sentence, and A is the second sentence.

See what the third teacher says: Ding is the second mistake, so A is the third right. Another teacher says Ding is the fourth right, and B is the first wrong, so B is the second.

If the first teacher says A is the second pair and C is the first mistake, then the third teacher is completely wrong. So we can't do this.