Natural unemployment is unemployment caused by some insurmountable reasons in the economy. It is unemployment that is unavoidable in any economy, and it is normal unemployment. Based on the above definitions, which of the following do not belong to natural unemployment? ['Zhang tried a month in a factory and suspected that the boss gave him a low salary, so he fired the boss\' "squid".', 'Water flooded somewhere and destroyed the plant and equipment, and the factory director dismissed the workers who followed him for many years.', 'An enterprise has been restructured according to the requirements of the city, and some female employees who have a low level of education and have reached the age of 45 have been laid off.', 'Li Mou helped a friend to ask for debt, and injured the debtor by accident. The company fired Li on the ground that Li violated labor discipline.']