THE widow of a worker who died after being hit by a collapsed wall has filed a writ with the Supreme Court seeking damages from his employers. Mrs So Tai-tai says the accident that killed her husband, Mr Cheung Kin-wai, 32, was caused by negligence by Gammon Construction in allowing him to work near a dangerous place. Gammon was responsible for work at the Diamond Hill MTR station entrance and Mr Cheung was assigned to break concrete. He died on January 1, 1991, after a 1.8-metre wall collapsed and hit him. A hospital worker who slipped on a greasy floor while cleaning is suing the Government for damages. Ms Ng Siu-mui, 38, says the accident in December 1988 at the Prince of Wales Hospital was due to negligence by the defendant, the Attorney-General, who is sued on behalf of the Regional Director (New Territories East) of the Hospital Services Department.