Use the be-passive form of the verb in brackets in the past simple. A blue ribbon is the topic, but the person responsible is unknown and must be omitted: it ___ to the garden gate overnight. (tie)

Բացատրություն

Was tied forms the requested past simple be-passive and leaves the unknown person unmentioned. Got tied is a standard informal get-passive, but it falls outside the be-passive construction specified by the instruction.