As is know, the passive voice structure is: subject + auxiliary very(be) + participle verb. But in some case, some sentences in passive voice don’t have an auxiliary very be. For instance: The problem solved itself. A book entitled New Concept English, etc.
The question is: When can the auxiliary verb(be) be omitted in a passive voice sentence?
The conference held yesterday was very interesting.
“held” is not the passive voice of the verb ‘to hold’, but a non-finite form called past participle. It is built up without any auxiliaries. In this sentence it serves as an attribute, modifying the subject ‘conference’.
The conference |(that was) held yesterday | was very interesting.
I would like to comment on the two examples you gave since you seem to be trying to compare apples with oranges:
The problem solved itself.
This is a complete sentence, but the verb form is not passive. The word “solved” in that sentence is the past simple tense in the active voice. The word “itself” makes the sentence reflexive-- i.e. the subject acted on itself.
A book entitled New Concept English
This is not a complete sentence, but rather a fragment. This phrase basically acts as a unit as either the subject or the object of a complete sentence. As is also the case with Pokeman’s example, the word “entitled” might be viewed as a shortened form of a relative clause containing a passive verb form:
A book |(which/that is) entitled New Concept English |
[size=75]“A man is not an orange. You can’t eat the fruit and throw the peel away.” ~ Arthur Miller[/size]
Wikipedia says: Although the passive voice, when used in the predicate verb of a complete sentence, requires the past participle to be accompanied by a form of be or another auxiliary verb, the past participle alone usually carries passive force; the auxiliary verb can therefore be omitted in certain circumstances, such as signs, newspaper headlines, and reduced relative clauses.
And Wiki provided some examples:
Couple found slain; Murder-suicide suspected.
The problem, unless dealt with, will only get worse.
A person struck by lightning has a high chance of survival.
I’d like to know if Esl_Expert and Pokemon’s explanations apply to these sentences in italic as well? Thanks in advance.