Avoiding Sentence Fragments
A subordinate clause must be attached to an independent clause. If it is not, it becomes a sentence structure error called a sentence fragment. The above examples of subordinate clauses are fragments; they can be corrected by combining each with an appropriate independent clause, and making complex sentences:
Although the weather didn't cooperate, we had a good time.
As he was in a hurry, he didn't stop to chat.
If you really want to go, you have my permission.
Louis Riel, who led the Metis in the North West rebellions, was hanged for treason.
The most important thing to remember about all subordinate clauses is that they cannot stand alone as sentences; they must be combined with an independent clause to form a complex sentence:
Although the weather didn't cooperate (sentence fragment)
Although the weather didn't cooperate, we still enjoyed our picnic.
Note that the subordinate clause can precede or follow the independent clause:
Although the weather didn't cooperate, we still enjoyed our picnic.
We still enjoyed our picnic although the weather didn't cooperate.
When the subordinate clause precedes the independent clause, it is followed by a comma; the comma isn't necessary when the subordinate clause follows the independent clause.
Subordinate means of lesser importance. In a compound sentence, the clauses are both independent, and both the ideas they convey are given equal emphasis. In a complex sentence, the idea in the subordinate clause is not given equal emphasis; that is why the writer chooses to put it in the subordinate clause, thereby emphasizing the idea of the independent clause:
Although she was penalized for plagiarism, she was basically an honest person.
The writer of this sentence wants to emphasize the idea of the independent clause - that "she was honest," and to place less emphasis on the idea of the subordinate clause - that "she was penalized for plagiarism."
Although she was basically an honest person, she was penalized for plagiarism.
Here, the writer is emphasizing that "she was penalized for plagiarism" and placing less emphasis on the fact that "'she was basically honest."
The difference between the two sentences is subtle but clear.