Unit 3 We should obey the rules.,Lesson 18,Lets chant,Warm-up,Lead-in,Lets act!,You must .,You mustnt .,Presentation,Just practice,Presentation,Presentation,Practice,You must/mustnt,Practice,Lets act!,You mustnt litter.,Practice,Just write,Can you write them?,wait,take,young,child,children,people,Practice,Lets make and talk,Presentation,Lets chant,Summary,四会单词：,wait,如何表达必须和禁止做某事？,You must/mustnt,take,young,child,children,people,
