Use of Modals: Ought to

 
 1.  Ought to का प्रयोग Advice (सलाह) moral obligation (नैतिक दायित्व), Duty (कर्तव्य) को व्यक्त करता है। जैसे:
You ought to consult a physician, (Advice)
We ought to respect our parents. (Moral duty)
We ought to help our friends. (Moral obligation)
You ought to follow the advice of the doctor. (Advice)

 2.  Ought के साथ not का प्रयोग किसी दायित्व को पूर्ण न करने के सन्दर्भ में किया जाता है या Advice के रूप में किया जाता हैं जैसे:
You ought not to treat your friends like this.
Children ought not to watch T.V. so long.
You ought not to talk to the elders in this manner.
You ought not to smoke so much.

 3.  Ought to का perfect tense में प्रयोग व्यक्त करता है कि जो कार्य सम्पन्न होना चाहिए था वह कार्य नहीं किया गया। जैसे:
She ought to have invited him to the function. (But she didn't invite him.)
He ought to have helped him in that matter. (But he didn't help him.)
He ought to have opposed the move. (But he didn't oppose.)
They ought to have come in time. (But they didn't come in time.)
You ought to have stopped at the traffic light. (But you didn't stop.)

 4.  सामान्यतया ought to एवं should को समान अर्थ एवं समान प्रयोग के सन्दर्भ में एक जैसा माना जाता है लेकिन formal notices या अन्य कोई सूचना के लिए 'should' का प्रयोग किया जाता है, 'ought' का नहीं जैसे:
Students should be prepared to donate the blood.
Travelers should be in possession of the following documents.
On hearing the alarm bell, the students should leave their rooms immediately.

उपरोक्त वाक्यों में 'Ought to' का प्रयोग ही होगा।

 5.  Ought to का प्रयोग Present, Past, Future tense में समान रूप से हो सकता है। जैसे:
I ought to talk to him today.
I ought to talk to him tomorrow.
I know I ought to talk to him.
I know I ought to have talked to him.