Modals of Advice
We use should and ought to for giving advice.
You should go to the doctor. You look terrible. (It’s a good idea to go to the doctor.)
My brother ought to study a lot tonight.
They ought to buy a new car.
Is there a difference between should and ought to?
Both modal verbs are interchangeable in most cases. Ought to is rarely used in US English. The main difference between them is in their form. Ought is written with to most of the time, except questions tags and when there is no verb afterwards.
She should study more.
She shouldn’t study more.
Should she study more?
She ought to study more.
She ought not to study more.
Ought she to study more?
We should get some water for the way, oughtn’t we?
Tell me what you do, not what you ought.
We can also use must for giving strong advice.
You should go to the doctor. (It means to go to the doctor is a good thing to do.)
You must go to the doctor. (It expresses the urgency and necessity of the action. It is strong advice or warning for the person.)