Rewrite the sentences using the short form when the long form

В разговорной устной и письменной речи утвердительные и отрицательные формы глагола to be в the Present Simple и в the Past Simple употребляются в сокращенном виде.

Утвердительные формы to be в the Present Simple:

• am = m: I am a student. = Im a student;
• is = s: He is at home = Hes at home;
• are = re; We are friends = Were friends.

Отрицательные формы to be в the Present Simple:

• am not = m not: I am not a teacher = Im not a teacher;
• is not = isnt: She is not at school = She isnt at school;
• are not = arent: They are not old = They arent old. 

1. He is brushing his teeth. - Hes brushing his teeth. 2. Im doing a test. - I am doing a test. 3. We are not joking. - We arent joking. 4. I am not reading. - Im not reading. 5. They arent working. - They are not working.