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Writing: Grammar: Parts of Speech
The Substitution Test

Main Page: Parts of Speech
Page Contents
  1. The Substitution Test
      1. Nouns
      2. Pronouns
      3. Verbs
      4. Adjectives
      5. Conjunctions

The Substitution Test

If a word or phrase can substitute a word or phrase in a sentence; that is, the sentence is grammatical with the substitute, then the substitute has the same or similar function to the word substituted in that sentence. Sometimes, we cannot substitute a word or expression in the same place in the sentence as another word or expression, although the substitutions are nonetheless equivalent. For instance, see adjectives, where an adjective usually precedes a headword, but an adjectival phrase follows it. Also, it may be necessary to change the person of the verb.

Nouns

For instance, we can substitute Tom for Hermonie in the sentence:
Hermonie went home. r_arrow.gif Tom went home.
We know that Tom is a Proper Noun, and because substituting Tom for Hermonie makes a grammatical sentence, then we can conclude that Tom and Hermonie perform similar functions in the sentence. In fact, both are Proper Nouns.

Pronouns

We can substitute she for Hermonie in the above sentence:
Hermonie went home. r_arrow.gif She went home.
Because the sentence is grammatical, we can conclude that she and Hermonie have a similar function in the sentence. We know that Hermonie is a Proper Noun, and so she must be a Proper Noun, or a Pronoun.

Verbs

In the sentence below, we can substitute ran for helter-skeltered:
Tom helter-skeltered down the road. r_arrow.gif Tom ran down the road.
helter-skelter therefore has a function similar to ran. They are both verbs.

Adjectives

We can substitute big for black in the following sentence:
The black cat crossed the road.  r_arrow.gif The big cat crossed the road.

With adjectives, we might have to substitute a word before a noun with an expression after the noun.
We saw a tall man.  r_arrow.gif We saw a man who was tall
We cannot substitute the expression who was tall in the same place as the adjective tall in first sentence, but need to put it after the noun man. However, the expression who was tall has the same effect as the adjective tall, so it functions as an adjective.

Conjunctions

If we substitute however for but in the following sentence, we get:
Harry was usually mean but he always gave to charity. r_arrow.gif Harry was always mean however he always gave to charity.x.gif
Something is wrong. It isn't grammatical. If we read the sentence aloud, we have to pause before and after however, to make it sound idiomatic. In speech we have to separate the two clauses with a pause. In other words, we have to turn them into sentences. We write this as:
Harry was usually mean; however, he always gave to charity.
Or
Harry was usually mean. However, he always gave to charity.

We know and is a conjunction. It is a word that joins two clauses. And we cannot substitute however for and. So however does not join two clauses (although ";however," does). It seems that however modifies the previous sentence. It add information to or takes information away from the previous sentence. The word however is not a conjunction, but a linking adverb.











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