1. used to indicate duty or moral obligation
Usage: followed by ‘to’ + infinitive
2. used to indicate what is advisable or recommended
Usage: followed by ‘to’ + infinitive
3. used to indicate probability or expectation
Usage: followed by ‘to’ + infinitive

Examples

• You ought to tell the truth.
• We ought to leave early to avoid traffic.
• Children ought to respect their parents.
• You ought to see a doctor about that cough.
• The package ought to arrive tomorrow.
• Students ought to study for their exams.
• He ought to apologize for his behavior.