The principle of protection of trust is a basic principle of administrative law, which means that the government's actions or commitments to itself should be honorable, and should not be changed at will and capricious. According to the above definitions, Which of the following are violations of the principle of trust protection:. ['A city government requires rewards for individuals who can attract foreign investment. Zhao introduced a company from a country to invest in the city, but the city government refused to pay the reward afterward.', 'A provincial bureau of industry and commerce stipulated that foreign beer entering the local market must be approved by the bureau in advance, and special operating fees should be paid at the same time, which was later rescinded due to suspected administrative monopoly.', "A city's public security bureau intends to punish Qian for revoking his license. After investigation, it is confirmed that Qian's behavior is not illegal, so no penalty is imposed.", "A city's environmental protection bureau considers that its subordinate department has imposed a heavy punishment of 50,000 yuan on Sun, and changed it to a fine of 5,000 yuan."]