1 I have to wear a uniform.
I don't have to wear a uniform.
Do I have to wear a uniform?
I had to wear a uniform.
2 She has to work hard.
She doesn't have to work hard.
Does she have to work hard?
She had to work hard.
3 He can do what he likes.
He can't do what he likes.
He could do what he liked.
Can he do what he like?
4 We're allowed to wear jeans.
We aren't allowed to wear jeans.
Are we allowed to wear jeans?
We were allowed to wear jeans.