ACTIVE sentence into passive VOICE, the subject and the object EXCHANGE places. Here, the subject is 'they', while the object is 'her' and 'Bonafide certificate' is the adjective clause. So, as per the rule, in passive voice, the new subject WOULD be 'She' (the subjective form of the pronoun; as 'her' is the passive form). The simple past tense verb changes from 'denied' to 'was denied'. Rule: Passive voice gives more emphasis on the action than the agent; so if the agent is unspecified such as they, people etc., it can be OMITTED. Here, the agent is 'they', which is unspecified; and hence can be omitted in passive voice. The adverb phrase 'as she had failed in two courses' remains the same.Thus, the passive sentence is: She was denied the Bonafide Certificate as she had failed in two courses.