L e s s o n 1 8 we should obey the rules. Lets act! You must . You mustnt . Just practice You must/mustnt Lets act! You mustnt litter. Just write Can you write them? wait take young child children people Lets make and talk 四会单词：wait 如何表达必须和禁止做某事？ You must/mustnt takeyoung child childrenpeople Thank you.
