Why can Sun Zhongshan (Sun Yet-shan) be revered by both the Nationalists and Communists?

Why can Sun Zhongshan (Sun Yet-shan) be revered by both the Nationalists and Communists?2. Why does “the reality of Japanese power and invasion…hampered the Nationalists and indirectly aided the Communists in their rise to power” ? (as the author writes in page 181)3. Briefly describe the May Fourth Movement (its time, cause, consequences)4. Briefly describe the Long March (its time, cause, consequences)5. Briefly describe the Xian Coup (its time, cause, consequences)