The use of subordinate clauses as complements and modifiers and as modifiers of complements and of modifiers may produce sentences of great length and complicated structure.
Such sentences, if skilfully composed, are not hard to follow. Their analysis requires merely the intelligent application of a few simple principles which have already been explained and illustrated.
These principles may be summed up as follows.
I. All clauses are either independent or subordinate. A clause is subordinate if it is used as a part of speech (noun, adjective, or adverb). Otherwise, it is independent.
II. Coordinate means of the same rank in the sentence.
1. Two or more independent clauses in the same sentence are manifestly coordinate.
1. The fire blazed and the wood crackled. [Two declarative clauses.]
2. What is your name, and where were you born? [Interrogative clauses.]
3. Sit down and tell me your story. [Imperative clauses.]
2. Two or more subordinate clauses are coordinate with each other when they are used together in the same construction as nouns, adjectives or adverbs.
Such a group may be regarded as forming one compound subordinate clause.
1. The truth is that I have no money and that my friends have forsaken me. [Noun clauses.]
2. The Indians, who were armed with long lances, and who showed great skill in using them, made a furious attack on the cavalry. [Adjective clauses.]
3. When he had spoken, but before a vote had been taken, a strange tumult was heard in the outer room. [Adverbial clauses.]
In the first example, we have a compound noun clause.
In the second, we have a compound adjective clause.
In the third, we have a compound adverbial clause.
3. Coordinate clauses are either joined by coordinate conjunctions (and, or, but, etc.) or such conjunctions may be supplied without changing the sense.
1. The good-natured old gentleman, who was friendly to both parties, [AND] who did not lack courage, AND who hated a quarrel, spoke his mind with complete frankness.
III. A subordinate clause may depend on another subordinate clause.
2. The horse shied when he saw the locomotive. [The subordinate clause depends upon the independent (main) clause.]
3. The horse shied when he saw the locomotive, which was puffing violently. [The second subordinate clause depends upon the first, being an adjective modifier of locomotive.]
In such cases, the whole group of subordinate clauses may be taken together as forming one complex subordinate clause.
Thus, in the third example, when he saw the locomotive, which was puffing violently may be regarded as a complex adverbial clause modifying shied and containing an adjective clause (which was puffing violently).
From the principles summarized, it appears that….
Clauses (like sentences) may be simple, compound or complex.
1. A simple clause contains but one subject and one predicate, either or both of which may be compound.
2. A compound clause consists of two or more coördinate clauses.
3. A complex clause consists of at least two clauses, one of which is subordinate to the other.
The unit in all combinations of clauses is clearly the simple sentence, which, when used as a part of a more complicated sentence, becomes a simple clause.
The processes used in such combinations, as we have seen, are really but two in number - coördination and subordination.
Coördination of clauses produces compound sentences or compound clauses; subordination of one clause to another produces complex sentences or complex clauses.
Every sentence, however long and complicated, belongs (in structure) to one of the three classes - simple, compound and complex.