It’s cold at night so you must/can pack a blanket. The campsite is next to a lake so we has to/can go…

It’s cold at night so you must/can pack a blanket. The campsite is next to a lake so we has to/can go swimming. There are no tents at the campsite so you don’t have to/ have to bring your own. You can’t/mustn’t drop litter in the nature reserve. It’s hot in here. Must/Can you open the window, please? Помогите пожалуйста