Original sentence: Martial law was declared on May 20 by the socialist hardliner Li Peng, but no action was taken until June 4.Soldiers and tanks from the 27th and 28th Armies of the People's Liberation Army were sent to take control of the city on June 4
Edited sentence: Martial law was declared on 20 May by the socialist hardliner Li Peng, but no action was taken until 4 June.Soldiers and tanks from the 27th and 28th Armies of the People's Liberation Army were sent to take control of the city on 4 June