c) Rewrite sentences 1–5 in the negative.

Для отрицательной формы после глагола to be добавляется not.

1. Susan is not new to the school.
2. I am not 14 years old.
3. They are not in Room E.
4. He is not my best friend.
5. You are not in Grade 7.

Ответ: Susan isn’t new to the school; I’m not 14 years old; They aren’t in Room E; He isn’t my best friend; You aren’t in Grade 7.