The necessary condition is that without the antecedent (condition), there is no follow-up (result); the antecedent (condition), not necessarily the follow-up (result), is a condition that is opposite to the sufficient condition, sufficient and necessary condition. Which of the following are not necessary? ['Only by admitting mistakes can we correct them.', 'Master market information and marketable products.', 'If you do not respect others, you cannot be respected.', 'If you want the horse to run well, you must ask the horse to eat enough grass.']