GRAMMAR-3
People have asked for rules for the use of commas. There are many pages devoted to comma use in the text books, and there is a wealth of material on the internet. There is too much material to be summarized in a post, but I will list some rules which may be helpful.
Here are some basic rules:
Commas separate two independent clauses (clauses which could stand alone as complete sentences) when used with the coordinating conjunctions and, but, so, for, or, nor and yet.
The clock struck twelve, and I knew I was in trouble.
No one could predict where he was going, and no one wanted to ask.
Commas are used to separate items in a list but not before the final and.
Mary stuffed the donuts, candy and brownies in her purse.
He decided to take geology, geometry and physics at the same time.
Commas separate words that might be misunderstood.
What the problem is, is not clear.
Commas set off introductory material.
Having suffered heavy losses, the enemy withdrew.
Commas set off appositives (explanations).
John Smith, the sole surviving son, will inherit everything.
Commas set off non-essential clauses.
Mary Jones, the woman coming down the street, is my cousin.
One of the grammar books lists some comma faults as follows;
Do not use a comma when the clause is essential.
The man who is standing on the corner is my brother.
Do not use a comma to join two sentences.
Wrong: The circus is in town, I plan to go.
Right: The circus is in town. I plan to go.
Right: The circus is in town, and I plan to go.
Right: The circus is in town; I plan to go.
Do not run sentences together with no punctuation.
Wrong: The girl boarded the bus she didn’t notice the number.
Right: May be corrected as shown above.
Do not use a comma between adjectives that are not coordinate (which could not correctly be separated by and).
This is a beautiful race horse.
The knife has a sharp cutting edge.
These are just a few suggestions. Please consult the internet for detailed help.