Modals of Obligation include the use of Must, Have to, Ought to, and Need to. They have different levels that include a firm resolve or a smaller level of recommendation.
Must, Have to, are very strong
Should, Need to, and Ought to are weaker
Affirmative
Subject + Modal + Base verb + Complement?
I must go shopping today.
You should see a doctor.
We need to eat better.
They have to be on time.
She ought to go early.
Negative
Subject + Modal + Not + Base verb + Complement.
I must not trespass
You should not eat too much.
We don't need to work today.
I don't have to go.
They ought not to do that. (specific structure)
Yes and No Questions
Auxiliary Verb (Sometimes) + Modal + Subject + Base verb + Complement?
Must you always do that?
Should we leave now?
Do you need to work today?
Do you have to sing so loudly?
Ought you to keep doing that? (specific structure)
Wh Questions
Wh + Modal + Subject + Base verb + Complement?
What must we do?
Where should we go?
Why do you need to do that?
When do you have to be home?
How ought we to eat this? (specific structure)