1. I am very busy today. - I am not very busy today. 2. We are the students of the Moscow State University of Printing Arts. - We are not the students of the Moscow State University of Printing Arts. 3. Mary is a good student. - Mary is not a good student. 4. We had two lectures yesterday. - We did not have two lectures yesterday. 5. The students worked in the laboratory. - The students did not work in the laboratory.