ever since mr.smith (was elected) head of the town's community center, he has been holding at least two meetings per week

 

이게 문장인데

 

was elected가 어떻게 되는지 궁금해요

 

was elected 에서 이미 문장이 끝나지않나요 ?

 

head는 전치사가 아닌데  어떻게 was elected가 되나요 ?