公共场所标识含义 — 英语填空题
题目
Lily is in a shopping mall. She sees a sign near the lift: “Wet floor”. Then she sees another sign on the wall: “No smoking”. From the first sign, we know the floor is wet, so people ___ walk carefully (小心) there. From the second sign, people ___ smoke in the mall. (填 must 或 mustn't)