Klingon makes a clear grammatical distinction between necessity (must, need to, have to) and moral or social obligation (should, ought to).

1. Must / Need To / Have To

To express that something is necessary — that someone must or needs to do something — Klingon uses the verb suffix -nIS ("need").

• jISopnIS – I need to eat.
• qama' vIQaw'nIS – I must destroy the prisoner.

This suffix indicates that there is a requirement or obligation, often implying that consequences will follow if the action isn't done.

2. Should / Ought To

To express that someone should or ought to do something — not because it is required, but because it is the right, wise, or honorable thing — Klingon uses the verb tlheb ("urge"). The activity being urged is the object of tlheb.

This construction uses either 'e' or net to refer to the action being urged. The person being urged is the subject of the first verb.

• qagh vISop net tlheb – I should eat gagh. (It is urged that I eat gagh.)
• qagh DaSop 'e' vItlheb – I think you should eat gagh. (I urge that you eat gagh.)
• qagh vISop 'e' vItlheb – I know I should eat gagh. (I urge myself to eat gagh.)
• jISop 'e' Datlheb'a' – Should I eat? (Do you think I should eat?)

Note: You do not say something like qatlheb to mean "I urge you." The object of tlheb is the activity, not the person.

The construction follows this general pattern:

S 'e'/net tlheb

Where S is a full sentence expressing the action that is being urged.

• net tlheb – It is generally urged (no specific speaker).
• 'e' vItlheb – I urge that it be done.
• 'e' Datlheb – You urge that it be done.

Most often, the subject of tlheb is "I" or "you," but a third-person subject is also possible.