Thera are many sentences of English whose structure is not accounted for by the phrase structure rules given so far, including :
- Pretty girls whispered softly.
- The man with the hat smiled
- The teacher believes that the student knows the answer.
From this example we see that a determiner is optional in the NP. Moreover, two new lexical categories appear: adjective (Adj) and adverb (Adv). both optional. All this suggest modifications to both the NP rule and the VP rule :
NP --- (Det) (Adj) N2
VP --- V (NP) (PP) (Adv)
The addition of an optional adverb to the VP rule allows for four more sentence types :
The wind blew softly.
The wind swept through the trees noisily.
The wind rattled the windows violently.
The wind forced the boat into the water suddenly.
The NP in sentence (2), the man with the hat, is similar to the man with the telescope seen earlier, and has the following structure :
The NP rule can modified once to include the option of a prepositional phrase :
NP --- (Det) (Adj) N (PP)
Sentence (3) contains another sentence within it self. The inside sentence, the student knows the answer, is embedded in the larger sentence The teacher believes that the student knows the answer. What sould the phrase structure of this sentence be ? Before we attempt to answer this question, we should look at some other data.
As pointed out earlier, any number of adjectives may be strung together. For simplicity our rules will allow only one adjective and would need to be changed to fully account for Englis speakers knowledge.
That the student knows the answer is believed by the teacher.
That the student knows the answer disturbed the teacher.
In both cases the expression that the student knows the answer patterns like a noun phrase. Compare :
The child is believed by the teacher.
The child disturbed the teacher.
These example suggest that by putting the word that in front of a sentence, in will function like an NP. The phrase structure tree for (3), then, is :
We omit the internal structure of the embeded sentence because it's not relevant. Another NP phrase structure rule is suggested :
NP --- that S
This rule is different from previous rules in that it contain a word (that) rather than a category. In the next section we'll se how words are put into phrase structure trees in general. This rule is a special case.
We now see how the ability all speakers have to embed sentences within sentences, as illustrated by the cartoon at the beginning of this section, is chaptured.
here is an illustrative phrase structure tree :
We need one final NP rules we have discussed so far. These are all the phrase structure rules we will present in this chapter :
- S --- NP VP
- NP --- (Det) (Adj) N (PP)
- NP --- that S
- NP --- Pronoun
- VP --- V (NP) (PP) (Adv)
- PP --- P NP
A complete grammar of English would have many more such rules. However, even this mini-grammar can specify an infinite number of possible sentences due to the fact that several categories (S, NP,VP) appear on both the left and right sides of several rules. Thus the rules explain our memories can still produce and understand an infinite set of sentences.
There are still many sentence type of English not encompassed by these rules. Only in passing have we mentioned verbal elements such as the auxiliary verbs have or may in sentences such as He may have left early.
Nor have we explicitly accounted for the many types of determiners besides the articles the and a that may precede the noun in a noun phrase such as each, several, these, many of michael Jackson's, and so on.
Each boy found several eggs.
These girl sang many of michael jackson's songs.
Rules (3) and (5) show that a whole sentence preceded by the word that may be embeded in a VP. In other data, different forms of sentence may be embeded in the VP. (Their source is beyond the scope of this introduction.)
Hillary is waiting for you to sing. ( Cf. You sing.)
The host regrets the judge's having left early. (Cf. the judge has left early.)
The hostess wants the judge to laeve early. (Cf. The judge leaves early.)
