I'm having a hard time figuring out when, exactly, to put a comma before the word "and" in a sentence. Here are a few sentences which will help to illustrate my question:
"The distance between two consecutive pulses of energy in a periodic wave is called the wavelength and it is an important number that characterizes that particular wave."
If I had written this sentence, I would have put a comma before the "and." Is this incorrect? If so, why?
Here's another sentence I underlined:
"They are sometimes called 'eye safe' lasers, and are not considered hazardous even if the output beam is directed into the eye's pupil for long periods of times."
This sentence has a comma before the "and," but I'm not really sure why.
Again, my question is this: when should I put a comma before the word "and" in a sentence?
2007-11-15
10:00:30
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5 answers
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asked by
Anonymous