170 CHAPTER 5
object NP (a ring) shifted to the subject position. Second, the prepositionbyap-
peared, and the deep-structure subject (Fred) became the object of the preposi-
tion. Third,beand the past participle suffix appeared in the auxiliary, turning
the deep structure verbbuyinto a passive verb form.
The grammar rule represents these changes symbolically. In this rule, the
symbolfimeans “is transformed into”:
Passive Transformation Rule.NP 1 Aux V NP 2 (Fred bought a ring)fi
NP 2 Aux + be -ed/en V by + NP 1 (A ring was bought by Fred)With respect to sentence 5:
NP 1 = FredNP 2 = a ring
V = boughtT-G grammar is predicated on examining the history of a given sentence, and the
most effective way of doing so is through tree diagrams, which allow us to examine
the deep structure and its corresponding surface structure. The process, however, is
different from phrase-structure analysis because it requires a minimum of two trees,
one for the deep structure and one for the surface structure. For more complicated
sentences, there are more trees, each one reflecting a different transformation and a
different stage in the history of the sentence. A convenient guideline is that the num-
ber of trees in a T-G analysis will consist of the number of transformations plus one.
We can see how this process works by examining sentence 5a on the next page.
Passive Agent Deletion. In many instances, we delete the agent in pas-
sive sentences, as in sentence 6:
- The cake was eaten.
When the subject agent is not identified, we use an indefinite pronoun to fill
the slot where it would appear in the deep structure, as in 6a:
6a. [Someone] ate the cake.This deep structure, however, would result in the surface structure of sentence 6b: