Life can't be repeated, there is no regret medicine, don't test people, don't test human nature, you won't know how insidious people are and how greedy human nature is, you won't know that people will betray themselves for money, don't hurt people who are sincere to you, you will never know how fickle people are, don't test people, you don't know how cheap your sincerity is, don't test human nature, you don't know what people will do for benefits, don't test people, you don't know.