The cooerdinating conjunction need not actually appear in the sentence.  Its omission is then indicated by the punctuation:  [John wished to play Indian; Richard preferred another game].

+81.  Subordinate Conjunctions and Complex Sentences.+—­A subordinate conjunction is used to join a subordinate clause to a principal clause, thus forming a complex sentence.  The test to be applied to a clause in order to ascertain whether it is a subordinate clause, is this:  if any group of words in a sentence, containing a subject and predicate, fulfills the office of some single part of speech, it is a subordinate clause.  In the sentence, “I went because I knew that I must,” the clause, “because I knew that I must” states the reason for the action named in the main clause.  It, therefore, stands in adverbial relation to the verb “went.”  “That I must” is the object of “knew.”  It, therefore, stands in a substantive relation to the verb.

Subordinate clauses are often introduced by subordinate conjunctions (sometimes by relative pronouns or adverbs); but, whenever such a clause appears in a sentence, otherwise simple, the sentence is complex.  If it appears in a sentence otherwise compound, the sentence is compound-complex.

The different types of subordinate clauses will be discussed later.

SENTENCE STRUCTURE

+82.  Phrases.+—­Phrases are classified both as to structure and use.

From the standpoint of structure, a phrase is classified from its introductory word or words, as:—­

1. Prepositional:  [They were in the temple].

2. Infinitive:  [He tried to make us hear].

3. Participial:  [Having finished my letter].

Classified as to use, a phrase may be—­

1.  A noun:  [To be good is to be truly great].

2.  An adjective:  [The horse is an animal of much intelligence].

3.  An adverb:  [He lives in the city].

+83.  Clauses.+—­It has been already shown that clauses may be either principal or subordinate.  A principal clause is sometimes defined as “one that can stand alone,” and is therefore independent of the rest of the sentence.  This statement is misleading, for, although true in most cases, it does not hold in cases like the following:—­

1.  As the tree falls, so it must lie.

2.  That sunshine is cheering, cannot be denied.

The genuine test for the subordinate clause is the one already given in connection with the study of the subordinate conjunction.  It must serve the purpose of some single part of speech.  All other clauses are principal clauses.

+84.  Classification of Subordinate Clauses.+—­A. Subordinate clauses may be classified into substantive and modifying clauses.