Query: When did protests in front of Carrefour's stores occur in China?
Context: The government also began to patrol and censor the internet forums such as Sohu.com, with comments related to the Carrefour boycott removed. In the days prior to the planned boycott, evidence of efforts by Chinese authorities to choke the mass boycott's efforts online became even more evident, including barring searches of words related to the French protests, but protests broke out nonetheless in front of Carrefour's stores at Beijing, Changsha, Fuzhou and Shenyang on May 1.