Помогите что поставить must или must`t
1.When you go hiking through a forest you___________drop litter.
2.When you leave he hiking camp you____________leave a fire.
3.When the weather is very hot you ___________wear hats.
4.When you go down a slippery road you ___________be careful.
5.When you go trough a tunnel you___________roller-skate.