Free Grammar Help—Conjunctions and Clauses
By Peter J. Francis, HGPublishing Editor
Clauses in sentences can be joined by punctuation (often a comma) or punctuation plus some kind of conjunction. Let's review the difference between a clause and a phrase, explained on the page on sentences. A phrase is any group of related words. A clause is a group of related words containing a subject and a verb. Incorrectly connecting clauses often leads to run-on sentences.
RULE 1: Use a comma to separate main clauses joined by a coordinating conjunction (and, but, or, for, yet, and so.)
EXAMPLE: The students were delayed by the heavy rain, but they managed to get back to class on time.
Exceptions:
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In compound sentences, when one or more of the main clauses are very short, you may omit the comma. Example: Ask no questions and you’ll be told no lies.
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You may use a semicolon to separate main clauses joined by a coordinating conjunction, especially when you have already used commas within the clauses themselves. Example: Harvard University, one of the best universities in the United States, was renowned for its Philosophy department; although Professor Leary was no longer teaching.
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You may use a semicolon in place of a comma to separate long coordinated clauses or to indicate a stronger pause between clauses. Example: Between reading, grammar exercises and watching videos, our English lessons consisted of worksheets, tests and quizzes; but still we had fun.
RULE 2: Use a semicolon to separate main clauses not joined by a coordinating conjunction.
EXAMPLE: Sometimes we work on grammar worksheets; other days we discuss our novel studies.
RULE 3: Use a semicolon to separate main clauses joined by conjunctive adverb.
(Conjunctive adverbs: however, nevertheless, moreover, therefore, consequently, hence, indeed, likewise, furthermore, namely, still and then.)
EXAMPLE: We went to the mountains to go skiing; however, the rain washed the snow away.
Note that when the conjunctive adverb comes within the second main clause instead of at the beginning, the clauses still must be separated by a semicolon, and the conjunctive adverb set off by commas.
Example: Canadians spend millions of dollars for road-building; our roads, however, are still full of pot holes.
Conjunctive adverbs are different from subordinating conjunctions. A conjunctive adverb is primarily a transitional word carrying the thought from one main clause to the next. Subordinating conjunctions introduce subordinate clauses. Subordinating conjunctions include: when, although, though, since, if, because, so that, as, after in order that, while and unless.
RULE 4: Use a colon to separate two main clauses, the second of which amplifies or explains the first.
EXAMPLE: The teacher posted a notice on the board: homework will be collected daily.