1.This is a book.–This isn't a book.
2.I can sing.–I can't sing.
3.I'm ten.–I'm not ten.
4.He was at home.–He wasn't at home.
5.I'll go tomorrow.–I won't go tomorrow.
6.She watches TV every day.–She doesn't watch TV every day.
7.I have been to Beijing.–I haven't been to Beijing.
8.My sister could speak English two years ago.–My sister couldn't speak English two years ago.
9.Lisa does her homework in the evening.–Lisa doesn't do her homework in the evening.
10.She has a computer.–She doesn't have a computer.
