From an answer on Quora:
"...the phrasal verbs are usually Germanic, and Germanic words in English are more often colloquial, whereas Romance words are more often formal. The colloquial/formal distinction (linguists speak of colloquial and formal registers) traces its origin, or so I have heard it theorized, to the process by which Middle English developed out of peasant Anglo-Saxon and elite Norman French."
To my understanding, according to this sentence, Middle English was affected by the process so is passive. If so why doesn't this sentence have a "was" in it? I mean isn't "the process by which Middle English WAS developed..." the correct one? Can you explain it to me?