Choose the correct answers for questions 1 to 6, and fill in the correct words (ie the right form of the negative of the verb 'be') for questions 7 to 12.
I ...... at school today.
am not
isn't
aren't
amn't
David ...... at the office today.
isn't
aren't
amn't
'm not
My friends ...... at home because they're at school.