Question

Cambiar estas oraciones a negativo e interrogativo Verbo to be:
-I am a good student
-We are old friends
-He is a student
-We are cousins
-Today is monday
-The sky is clear
-They are brothers
-He is lawyer
-She is in Europe
-Martha is angry

Answer 1

I am not a good students
Am I a good student?

We are not old friends
Are we old friends?

He is not a student
Is he a student?

We are not cousins
Are we cousins?

Today is not Monday
Is it Monday today?

The sky is not clear
Is the sky clear?

They are not brothers
Are they brothers?

He is not a lawyer
Is he a lawyer?

She is not in Europe
Is she in Europe?

Martha is not angry 
Is Martha angry?

Para las negaciones se agrega NOT luego de la forma del TO BE. Para preguntar se antepone la forma del verbo TO BE al sujeto y se finaliza con signo de pregunta.

Espero haberte ayudado!