Subordinate Clauses

A. Recognizing Clauses
Consider these examples:
clause :cows eat grass
This example is a clause, because it contains the subject "cows" and thepredicate "eat grass."
phrase :cows eating grass
What about "cows eating grass"? This noun phrase could be a subject, but it has no predicate attached to it: the adjective phrase "eating grass" show whichcows the writer is referring to, but there is nothing here to show why the writer is mentioning cows in the first place.
Clause :cows eating grass are visible from the highway
This is a complete clause again. The subject "cows eating grass" and the predicate "are visible from the highway" make up a complete thought.
Clause :Run!
This single-word command is also a clause, even though it does seem to have a subject. With a direct command, it is not necessary to include the subject, since it is obviously the person or people you are talking to: in other words, the clause really reads "[You] run!". You should not usually use direct commands in your essays, except in quotations.

Practice :Identifying Clauses
Some of the following passages are clauses, while others are simply phrases. Mark C for clause and P for phrase.
I love to eat Montréal bagels
the big, bad wolf
rode the bus to Halifax
they were thinking about the language issue
the student considering everything written on this subject
stay on the Trans-Canada highway through British Columbia
after the morning rush hour
they hate politics
because of the coat which I bought in the West Edmonton Mall
when the train arrived at the station

B. Using Clauses as Nouns, Adjectives, and Adverbs
If a clause can stand alone as a sentence, it is an independent clause, as in the following example:
Independent :The Prime Minister is in Ottawa.
Some clauses, however, cannot stand alone as sentences: in this case, they aredependent clauses or subordinate clauses. Consider the same clause with the subordinating conjunction "because" added to the beginning:
Dependent :when the Prime Minister is in Ottawa
In this case, the clause could not be a sentence by itself, since the conjunction"because" suggests that the clause is providing an explanation for something else. Since this dependent clause answers the question "when," just like anadverb, it is called a dependent adverb clause (or simply an adverb clause, since adverb clauses are always dependent clauses). Note how the clause can replace the adverb "tomorrow" in the following examples:
Adverb : The committee will meet tomorrow.
adverb clause : The committee will meet when the Prime Minister is in Ottawa.
Dependent clauses can stand not only for adverbs, but also for nouns and fore adjectives.

1. Adjective Clauses
An adjective clause is a dependent clause which takes the place of an adjective in another clause or phrase. Like an adjective, an adjective clause modifies a noun or pronoun, answering questions like "which?" or "what kind of?" Consider the following examples:
Adjective :the red coat
Adjective clause :the coat which I bought yesterday
Like the word "red" in the first example, the dependent clause "which I bought yesterday" in the second example modifies the noun "coat." Note that an adjective clause usually comes after what it modifies, while an adjective usually comes before.
In formal writing, an adjective clause begins with the relative pronouns"who(m)," "that," or "which." In informal writing or speech, you may leave out the relative pronoun when it is not the subject of the adjective clause, but you should usually include the relative pronoun in formal, academic writing:
Informal : The books people read were mainly religious.
Formal: The books that people read were mainly religious.
Informal : Some firefighters never meet the people they save.
Formal : Some firefighters never meet the people whom they save.
Here are some more examples of adjective clauses:
the meat which they ate was tainted
This clause modifies the noun "meat" and answers the question "which meat?".
about the movie which made him cry
This clause modifies the noun "movie" and answers the question "which movie?".
they are searching for the one who borrowed the book
The clause modifies the pronoun "one" and answers the question "which one?".
Did I tell you about the author whom I met?
The clause modifies the noun "author" and answers the question "which author?".

2. Adverb Clauses
An adverb clause is a dependent clause which takes the place of an adverb in another clause or phrase. An adverb clause answers questions such as "when?", "where?", "why?", "with what goal/result?", and "under what conditions?", etc.
Types of adverb clauses :
Subordination conjunctions :
Time :after, before, until, while, since, as