undersökt

In a sentence

• Jag har undersökt saken noggrant.

  I have examined the matter thoroughly.

  Here 'undersökt' is used as the past participle of the verb 'undersöka', indicating a completed investigation.

• Den nya modellen måste undersökas innan produktion.

  The new model must be examined before production.

  In this sentence, 'undersökas' is used as the passive form of the verb, indicating that the investigation needs to be performed.

• Han hade redan undersökt området när vi anlände.

  He had already explored the area when we arrived.

  'Undersökt' in this context is the past perfect form of the verb, emphasizing that the exploration had already occurred prior to another event.