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*Asterisk = examples of errors or poor constructions*.
Student Learning: Grammar
Using commas - Lesson three
- 3.1 In front of conjunctions:
Commas are commonly used before a joining word when linking two complete independent sentences. A complete sentence is one that can exist by itself and makes complete sense (... it has its own subject and its own verb). A joining word (conjunction) are words such as and, but, although, or, when, if.
If either of the two phrases within a sentence are not complete (for example they don't have their own subject or their own verb), then no comma is used before the joining word. Look at the examples below to see this demonstrated.
I knew the opposition were good, but I had never seen them play.
I knew the opposition were good but had never seen them play.
I went to France for my first overseas experience, and my wife chose to join me there later on.
You have to be a little careful with this advice. A comma can be ommitted before conjunctions joining two short complete sentences (see example below)...
... and a comma alone (without a conjunction) is not enough to join two complete complex sentences. You need to be careful not to create a comma splice... (See the Comma Splice lesson for an explanation about this error.)
- 3.2 For isolating information:
A comma may be used to isolate (incomplete) ideas appearing either at the beginning or at the end of their attendant independent clause. While he comma is not always necessary, it might be desirable to help with the meaning.