Помогите пожалуйста сделать номер второй .Я не поняла как его делать.

Заподни пропуски с must и mustn't
И ты получишь песню

School uniform Every day!
Who looks cool
In blue and grey?
You must  wear jeans
And you shoes  are not clean.
You must be here
At eight fifteen.
You must not wear shorts 
(I do not know why)
You must not run in corridors
And where is you tie?
You must tell a teacher 
If you feel in danger.
You must ask first
Before you go with a stranger.