Test analysis: According to the perfect score of 100, if the sum of two people's scores is 160, even if one person's score is 100 and the other person's score is 60, their score difference will not be 60. Therefore, proposition 2 is correct.

Solution: If Li Hua's statement is a true proposition, the sum of the scores of two people is 160.

If one of them gets 100 and the other gets 60, then their scores have the biggest difference, that is, 100-60=40 < 60.

So one of them must be lying, so the true proposition of this question is ②.

Comments: The key to solving the problem is to read the meaning of the question, carefully analyze the language characteristics of two people, and be able to analyze and judge according to the full score of 100.