Apart from an intro line that repeats once and a bridge, this song also seems to be almost all chorus.
Call it perhaps a chorus that functions like a verse; it begins with a refrain line and then has different words that follow in each of its three utterances.
Is sixteen bars too long to call it a chorus? Maybe, but the last four bars are like an extension and are not even played the third time through.
Three utterances, that intro line that repeats once, and a bridge - I wonder how many other hit records from 1969 were under two and a half minutes.