Составить 5 предложений на языке что следует и что не следует делать

You must do your exercises
you must eat
you must save your books
you must do your homeworks
you mustn't do bad things
you mustn't be lazy
you mustn't cry
you mustn't stay at home on workdays
you mustn't paly more computer

Не следует:
we shouldn't cut trees.
people pollute rivers, lakes and seas.
we shouldn't kill animals.