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Passives
In passive constructions such as ((129)), the subject NP is
interpreted as having the same role as the direct object NP in the
corresponding active declarative ((130)).
(128)0(128
- (129)
- An airline buy-out bill was approved by the House. (WSJ)
(129)0(129
- (130)
- The House approved an airline buy-out bill.
Figure:
Passive trees in the Sentential Complement with NP tree family: nx1Vs2 (a), nx1Vbynx0s2 (b) and nx1Vs2bynx0 (c)
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In a movement analysis, the direct object is said to have moved to the subject
position. The original declarative subject is either absent in the passive or
is in a by headed PP (by phrase). In the English XTAG grammar,
passive constructions are handled by having separate trees within the
appropriate tree families. Passive trees are found in most tree families that
have a direct object in the declarative tree (the light verb tree families, for
instance, do not contain passive trees). Passive trees occur in pairs - one
tree with the by phrase, and another without it. Variations in the
location of the by phrase are possible if a subcategorization includes
other arguments such as a PP or an indirect object. Additional trees are
required for these variations. For example, the Sentential Complement with NP
tree family has three passive trees, shown in Figure 12.1: one
without the by-phrase (Figure 12.1(a)), one with the by phrase before the sentential complement (Figure 12.1(b)),
and one with the by phrase after the sentential complement
(Figure 12.1(c)).
Figure 12.1(a) also shows the feature restrictions imposed on
the anchor12.1. Only
verbs with <mode>=ppart (i.e. verbs with passive morphology) can
anchor this tree. The <mode> feature is also responsible for
requiring that passive be adjoin into the tree to create a matrix
sentence. Since a requirement is imposed that all matrix sentences must have <mode>=ind/imp, an auxiliary verb that selects <mode>=ppart and <passive>=+ (such as was) must adjoin
(see Chapter 20 for more information on the auxiliary verb
system).
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Up: Sentence Types
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XTAG Project
1998-09-14