must/mustn't表必须与禁止 — 英语词汇题
题目
根据句意及首字母提示补全单词：1. You mustn't t______ the wet paint on the wall. 2. Passengers must w______ for the green light before crossing the road. 3. You mustn't play with f______, or you may start a fire. 4. We must k______ away from the deep water when swimming alone.