A venomous snake designated the emblem of the rebellion by the insurgency
The solution mark the clause as incorrect, the correct one being
A venomous snake was designated the emblem of the rebellion by the insurgency
The book explains that the original sentence is a fragment, with designated as a past participle
I thought the original sentence was correct, with "designated" being not a past participle, but a past simple. A past simple should be a working verb, so the sentence is not a fragment
1. Can you explain why my reasoning is incorrect?
2. While I understand that a participle alone cannot be a working verb, how can I discern a past participle from a past simple?
Thanks