Something must be done with the police salary.

The laws in our country ought to be changed.

I wish I didn't have to go to work today.
I wish I hadn't eaten so much.

Today teachers and students have being trampled. It seems they can't to protest in this country.I think the goverment  does't have the polítics intetions to solve UASD problems.

So they want four more years.

Everybody must wear a uniform in the class.

If you feel bad you should go to the doctor.

Modals

I must do my homework, because if I don´t do it, I couldn´t understand the subject.