Test analysis: China's democratic revolution is divided into two stages: the old democratic revolution and the new democratic revolution. The May 4th Movement marked the replacement of the old democratic revolution by the new democratic revolution, not the beginning of the democratic revolution in China. The democratic revolution in China began after the Opium War of 1840, so A was chosen.
Comments: Why is the May 4th Movement the beginning of China's new-democratic revolution? (1) From the leadership point of view, from the May 4th Movement, the working class in China began to step onto the political stage and played a major role in the movement. (2) From the revolutionary guiding ideology, after the May 4th Movement, the spread of Marxism became the mainstream of the New Culture Movement and gradually combined with the workers' movement. (3) From the perspective of the future of the revolution, the purpose of the working class is not only to crush the old world, but also to establish a new society different from the former regime-after the victory of the democratic revolution, a socialist capitalist society will be established.