题目内容：

九年级英语句子改写,有例句
例：Can I climb that tree?(not allowed)~You aren't allowed to climb that tree.
1.Please don't enter without knocking.(mustn't)~
2.I'd like to walk across the grass.(can't)~
3.Let's take some photographs in the Science Museum.(not allowed)~
4.Stop chatting,please.(mustn't)~