"Pluperfect is used to locate a situation in the past prior to a reference point that is also in the past, thus, it can be regarded as 'past in the past'. (Comrie 1985: 65). Whereas in example (1) the referece point is established by the subordinate clause, in example (2) it becomes clear from the context that an action was completed by a certain point in the past. Past perfects may be realised by periphrastic (1) or by synthetic means (2)."