Some modifiers expand units within a sentence. For example, adverbials add information about verbs, and adjectivals add information about nouns.  Unlike these constructions, the ones described below do not have a clear connection to a particular sentence slot. Instead, the information they give us relates to the entire sentence; in other words, they are SENTENCE MODIFIERS.  The information below focuses on two particular sentence modifiers,  SUBORDINATE AND RELATIVE CLAUSES.
 

Definitions

• Sentence modifier: a word, phrase, or clause that comments on an entire sentence instead of a specific slot of a sentence. (Obviously, she did not know the correct answer.)
• Subordinate clause: a clause (a phrase with a subject and a tensed verb) that can't stand alone and begins with a subordinating conjunction such as if, since, as, because, and although. Subordinate clauses can modify a verb or, as in the following example, the entire sentence. (Although I could easily have refused, I accepted the job.)
• Relative clause: a clause (a phrase with a subject and a tensed verb) that begins with one of the relative pronouns (who, whom, which, that) or relative adverbs (when, where, why). Relative clauses can modify a noun or, as in the following example, the entire sentence. (She assigned three assistants to my crew, which made the project more appealing.)
• Interjections: a single word or phrase that has no grammatical function in a sentence, but provides information about the speaker's attitude. (Wow, grammar is interesting!)
• Absolute phrase: a noun phrase that includes a postnoun modifier (commonly -en and -ing participle or participial phrase) and introduces an idea related to the sentence as a whole. (Its flag whipping in the wind, the ship entered the harbor.)

    Question:  When is a subordinate clause a sentence modifier?  Answer:  When it relates to the sentence as a whole instead of only one part or slot of that sentence, the subordinate clause can be considered a sentence modifier.

    Example: If she passes calculus this semester, she will graduate on time.

The following chart, adapted from a list in Understanding English Grammar, by Martha Kolln and Robert Funk, can help you identify the words that introduce subordinate clauses.
 
 

Simple Subordinators  Time:  when, whenever, after, before, once, until, as  Concession:  though, although, if, while  Condition:  if, unless  Reason:  because, since  Result:  so  Comparision:  as  Contrast:  while, whereas

Phrasal Subordinators  Time:  as long as, as soon as  Concession:  even though  Concession:  in case, as long as, provided that  Reason:  as long as  Result:  so that  Comparison:  just as , as if

 
 
Tips:     When a subordinate clause opens a sentence, set it off by commas.
                  When a subordinate clause closes a sentence, the punctuation is  related to
                   its meaning.
                   The difference between an adverbial and a subordinate clause is that the
                   adverbial refers to the verb, and the subordinate clause refers
                   to the entire sentence.
 
Exercises:  Identify the subordinating conjuctions in the following sentences.

1.  As Ford Motor company goes, so goes the nation.
2.  When he arrived, he began to sing a song.

Identify the subordinate clauses in the following sentences.

1.  The Executive Board members, before they adjourned the meeting, voted to give a  reward to the new chairman.
2.  Many of the players, as they sat in the dugout, heard the cheers from the crowd.

Relative Clauses:
 
 
 

Common Relatives:                                   Pronouns:   who, whom, whose, which, that                                          Adverbs:  where, when, why

 
 

Tips:  Relative clauses tend to be modifiers of nouns.
Example: Amy's jacket, which she bought last month, looks like it's been torn.
 
When dealing with relative clauses, you may come across broad-reference clauses that begin with which.  You must set them off with commas because they are nonrestrictive.
Example: The boys left the park in a hurry, which leads me to believe they had been mischievious.
 

 
Exercises:  Rewrite the following sentences to eliminate the broad reference    which.
 
1.  I had to write a paper for CMA 106, which wasn't very much fun.
2.  I ran to the store from my house, which turned out to be a mistake.

Click here for answers.