1) 1. isn't 2. am 3. aren't 4. is 5. are 6. aren't 7. am not 8. is.
2) 1. It isn't at three o'clock. It's at four o'clock.
2. You aren't fifteen. You are fourteen
3. she isn't in a chess club. She's in a climbing club.
4. We aren't from Czech Republic. We're from Hungary.
5. They aren't in London. They're in New York .
6. You aren't Emily. You're Kate.