must/mustn't 表示必须与禁止 — 英语选择题
题目
Ben is at the museum. There is a sign on the wall: 'You mustn't touch the paintings.' But he wants to touch one. His mother says rules are important. What must Ben do? A. He must touch the paintings. B. He mustn't touch the paintings. C. He must run in the museum. D. He mustn't follow the rules.