There are two voices in English, the active voice and the passive voice:
|Active Voice||Passive Voice|
| Paul congratulated David|| David was congratulated by Paul|
Passive constructions are formed using the PASSIVE AUXILIARY be, and the main verb has an -ed inflection. In active constructions, there is no passive auxiliary, though other auxiliaries may occur:
Paul is congratulating David
Paul will congratulate David
Paul has congratulated David
All of these examples are active constructions, since they contain no passive auxiliary. Notice that in the first example (Paul is congratulating David), the auxiliary is the progressive auxiliary, not the passive auxiliary. We know this because the main verb congratulate has an -ing inflection, not an -ed inflection.
In the passive construction in , we refer to Paul as the AGENT. This is the one who performs the action of congratulating David. Sometimes no agent is specified:
David was congratulated
We refer to this as an AGENTLESS PASSIVE.