Consider that they are intransitive Verbs, then, can they be turned into Passive Voice? As I know, Intransitive Verbs can't be turned into Passive Voice as they don't have objects. However, I still find the example of passive Voice for these Verbs.
ex:
- the Royal Navy is referred to as the Senior Service. (from http://www.oxforddictionaries.com/definition/english/refer)
Hi Zoe
"Refer" is indeed an intransitive verb when it means 'mention' or 'allude to', but it's one of those verbs that selects a specified preposition and is thus called a 'prepositional verb'. In such cases, a construction called a prepositional passive is often possible. Consider:
*"Ed referred his book". ~ *"His book referred by Ed".
"Ed referred to his book". ~ "His book was referred to by Ed".
* = ungrammatical
So your example is fine:
"Most people refer to the Royal Navy as the senior service". (active clause)
"The Royal Navy is referred to as the Senior Service by most people". (passive clause)