Punctuating Sentences with Subordinate Clauses

Punctuating Sentences with Subordinate Clauses

1. If you begin a sentence with a subordinate clause, use a comma after the subordinate clause: When they arrived, we cheered the tall ships.

2. In general, you do not need a comma before a subordinating conjunction that appears toward the end of the sentence, particularly if it begins a restrictive clause. If the restrictive clause were removed, the meaning of the sentence would differ greatly. We cheered the tall ships when they arrived. Not many people paid attention to the scandal because Bill Clinton had high ratings. (The later information is crucial to understanding the first part of the sentence.)  Please make the copies of the final report today, because I am leaving for a business meeting tomorrow morning. (The second clause can be a separate sentence, so it is nonrestrictive.)

3. If the subordinating conjunction is though or although, do use a comma before it: We cheered the tall ships, although their sails were not up. Bill Clinton had high ratings, though he was immersed in scandal.

4. Do not use a comma before as, while, or since if you mean "when." We cheered the tall ships as they came into the harbor.

5. Do use a comma before as or since if you mean "why" and before while if you mean "whereas." We cheered the tall ships, as they were a symbol of past greatness.