Look at the examples. What is an imperative? How do you make the negative form?

Fly north.
Swim in the river
Don't fly north.
Don't swim in the river​​

I don't like to be engaged in house affairs, but it's necessary. Our apartment is large, and our mother can't do everything alone. We distributed the responsibilities in the home, and it certainly becomes easier. My sister and I are responsible for cleaning of the rooms, we sweep the floor, water our mother's flowers in the pots. It seems they are everywhere: in the kitchen, in the rooms, in the bedroom, in the boxes on the floor. My brother takes out the rubbish and keeps order on the balcony. The carpets are daddy's responsibility. But we enter the kitchen, only to have breakfast-lunch-dinner. This is our mother's territory. We believe that by doing things together, we are real power. A family.

                                                                                                   Mira street, 32
                                                                                                   (город)
                                                                                                   Russia
                                                                                               The 17th of October
Dear Tom,
Thank you for your letter. I did not write you because I was ill.
It is great that you passed your Russian exam. Recently I had an English exam. Preparation for it was not so hard. I had evaluation of 4. I had some grammar mistakes but a letter and essay were so good. Also my monologuу and dialog were good too.So I want to ask you some questions. How would you prepared for your exam? What were tasks in it? How good do you know Russian language?
Oh, sorry Tom, I am hurry. That is why I must finished my letter. I send you greetings.
Goodbye
Write back soon 
(имя своё)