USED THE SHOULD, OUGHT TO, HAVE TO

Should, ougth to, and have to are modal verbs. Use should and ought to to give
advece or to talk about what is right to do. Use shouldn´t to talk about something that is
not right to do. Use have to or has to to talak about something that you must do, something
that is necessary. Use don´t have to or doesn´t have to to talk about something that is not
necessary.
In affirmative and negative statements, SHOULD, SHOULN*T and OUGHT TO
are followed by the base form of the verb. The modal verb and the main verb
stay the same for each person.

I
YOU
HE
SHE SHOULD
IT OUTH TO GO ON A DIET
WE SHOULDN´T
YOU
THEY

Use Have to and don¨t have to with I, YOU, WE, AND THEY.
I Have to see the doctor.
YOU Don´t have to go to work when you´re sick.

Use Has to and doesn¨t have to with HE, SHE, OR IT.
SHE Has to take her medicine every day.
HE Doesn¨t have to have surgery.

In wh-questions, use should to aks for advice. Ought to is rarely used
in questions or negatives.

WHAT SHOULD I do to lose weight?
WHY SHOULD He see the doctor?