As we've just seen, words don't get put into sentences on a one-by-one basis, instead they combine together in certain ways to form phrases, and the phrases combine to form sentences.

By the way, Steven Pinker wrote a book entitled Words and Rules, so I am blatantly plagiarizing.

Activity: Phrase Structure

Clue Phrase Structure Activity

Since one group of words can combine with another group of words to form yet a third group, we need a way to talk about this process.
We use the terms:

• word,
• phrase,
• clause and
• sentence to describe the relationships.
  

• A constituent is any element that is a smaller part of a larger element.
  • Words are constituents of phrases
    • Phrases are constituents of clauses and sentences.
      
      
• Since words are smaller parts of phrases, they must also be smaller parts of sentences, so we can say that words are constituents of sentences, too.

Some constituents you probably learned in grade school are subject and predicate. You may also recall that every predicate must have a verb. A more accurate term for predicate is Verb Phrase, then, since a verb is a required constituent in that group of words.

When we give a grouping of words a name, we name it after its required constituent.
The required constituent itself is called a head.

A predicate is called a verb phrase, so it follows that the appropriate term for the subject is a Noun Phrase.

Other phrases are:

• Adjective Phrase
• Adverb Phrase
• Prepositional Phrase
  

Now we can try to explain one of the ungrammatical sentences.

*Jane bought a necklace blue.

There isn’t anything wrong with the words in this sentence, just the order they are in.

First let’s figure out what kind of phrase a necklace blue is.

a is a determiner. necklace is a noun. blue is an adjective.
This is then a Noun Phrase.
Let’s use the abbreviation NP

What then, is the proper word order for a noun phrase?

Whereas a NNS may not know this, a native speaker would understand that the adjective comes before the noun, and that the determiner comes before any adjectives. Properly stated, the phrase would be: a blue necklace.

So we might come up with a rule like this: NP → a blue necklace
But, of course, that’s only for this sentence alone. We can make it a rule for all noun phrases by using the syntactic categories of the words instead of the words themselves.

We get something like this:
NP → Det A N

If you try it out, you will find that this rule works for other noun phrases.

Suppose we want to write a rule for verb phrases, what might it look like?
Let’s start with a grammatical sentence:

Jane bought a blue necklace.

The verb phrase consists of the verb and the object with all it's modifiers. We have already determined that the object, as a whole, is a noun phrase. So, a generic rule for a verb phrase can be written as:

VP → V NP

Remember that some verbs are transitive and some are intransitive?
Now we need to show that Verb Phrases need a verb, but don’t always need an object.
That is done with this form of PSR.

VP → V (NP)

The parentheses show that an object is a possible, but not required, constituent. We call it an optional constituent.

Phrase structure rules show how to combine words together into phrases, and we can show the rules for combining phrases into sentences using the same method.

A sentence would be represented as:

S → NP VP

Once the phrase structure rules are figured out, we can test them by analyzing sentences to see if real sentences follow the rules we’ve written.

We can analyze sentence structure the same way we analyzed word structureby using Labeled Bracketing; with the same lousy results.

Or we can use tree diagrams. These are done very much like the diagrams for word formation.

Activity: Sentence Diagrams

And since it’s really hard to make tree diagrams of sentences on the computer, just do these on a piece of paper. Each example is linked to a computer drawing. Try the exersise before you check your answer.

Mouse over the Answer link to see finished diagram.

Sentences to analyze:

Teaching Language

Word order can be tricky because the rules of English might be different from rules of the native language.
One issue for some learners: standard English doesn’t like repetition of subjects or objects. Such repetition is, in fact, often considered ungrammatical.

*My sister she is a doctor.
*Our house we painted it last week.