In English, when you want to express a fact about a state or description, you use "that" followed by a clause: "I know that the building is old." Because "the building is old" does not contain an action verb, it is a nominal sentence.
To embed a nominal sentence as an object in Turkish, use the helper verb olmak (to be) together with the factive -dIk suffix.
To say "that [Subject] is [Adjective/Noun]" in Turkish, follow this structure:
- The subject of the embedded clause takes the genitive case (e.g., binanın, the building's).
- The adjective or noun describing it stays in its plain form (e.g., eski, old).
- Add olduk (the verb olmak
- Attach a possessive suffix to olduk that matches the subject (usually the 3rd person singular -u, softening the k and becoming olduğu).
- Attach the case ending required by the main verb. For verbs like knowing, seeing, or thinking, this is the accusative case (-nu).
| Subject (Genitive) | Predicate | Helper Verb + Possessive + Case | Main Verb | English Translation |
|---|
| Binanın | eski | olduğunu | biliyorum. | I know that the building is old. |
Let's apply this structure using vocabulary related to urban planning and architecture:
Nouns as Predicates
The predicate doesn't have to be an adjective; it can also be a noun. The structure remains exactly the same. Conceptually, "that the houses are shanties" is phrased as "the houses' shanty being" in Turkish.
Complex Subjects
The subject of your embedded clause might already have its own suffixes, such as a noun compound or a possessive phrase. Simply add the genitive case to the very end of the subject phrase before continuing to the predicate and olduğu.
Different Case Endings on "Olduğu"
Most verbs that express thinking, knowing, stating, or realizing (like bilmek, düşünmek, fark etmek) take a direct object. This is why olduğu almost always takes the accusative case (olduğunu).
However, if your main verb requires a different case, the suffix on olduğu must change to match. For example, the verb inanmak (to believe) requires the dative case (-a / -e). Therefore, "that it is" takes the dative suffix and becomes olduğuna.
