情态动词must表达必须遵守的规则 — 英语词汇题
题目
根据句意和中文提示补全句子（每空一词，首字母已给出）。
1. You m____ stop when the traffic light is red.（必须）
2. We m____n't play with f____（火）at home.
3. You m____ look left and right before you cross the road.（必须）
4. Don't run down the s____（楼梯）. It's dangerous.