AN illegal immigrant whose case was repeatedly adjourned because he refused to speak was yesterday jailed for 15 months. Cheung Ming-wah, 25, first appeared in court last December but remained silent until February 16. He then admitted two of four charges against him after a medical report concluded that he had pretended to be deaf and mute. Cheung pleaded guilty to possessing an offensive weapon, last December and to unlawfully remaining in Hongkong. He denied resisting arrest and damaging a table at the Waterfront police station in Central. Magistrate Miss Loh Kim-wan jailed Cheung for 15 months for illegally arriving and remaining in Hongkong and two months for possessing an offensive weapon. The terms are to run concurrently. She dismissed the charges of resisting arrest and criminal damage after the Crown offered no evidence.