Ο Τζιμ συμπεριφέρονταν παράξενα όλη μέρα.

English Translation

Jim acted very strangely all day.

I think the correct spelling of the cloze word is συμπεριφερόταν or συμπεριφερότανε, which are third person singular. Συμπεριφέρονταν is third person plural. I have requested clarification from tatoeba.