All power company employees participated in the snow disaster relief work, and a certain armed police officer and soldier also participated in the snow disaster relief work. The armed police officer and soldier strengthened winter military training. Most of the staff in the railway department did not participate in the winter military training, but all participated in Earthquake relief work. Based on this, which of the following judgments is necessarily true? ? ['Some people who participated in the snow disaster relief work were employees of the power company.', 'Officers and soldiers of an armed police both participate in snow disaster relief and strengthen winter military training.', 'Some railway department staff participated in winter military training.', 'Some railway department staff participated in the snow disaster relief work.']