How to use comma in sentences?

[tesoke]

Hi, I have a problem with using comma in sentences and need help. There are three sentences of my writing that a teacher has revised them. He has proposed comma in all of them, and I cannot understand it these three proposed commas are obligatory or optional? And why? Would you please explain? Thanks.

- I believe this may be a boring deed[,]not an attractive pastime.
- If they miss a secure job, there is no assurance that they will find another job opportunity[,] even one similar to the missed job.
- Consequently, students waste many pleasant things because they are hard to do[,] such as attending classes.

 

[goldenband]

From a native speaker's perspective, I can say that I agree with your teacher in all three sentences -- the commas are indeed necessary.

I'm not sure of the grammatical term to describe why they're necessary, but I think it falls under the category of "contrasting ideas" or "contrasting elements". See here for one discussion of that; here is another. However your third example is probably a slightly different case.

 

[e2efour]

I am not disagreeing with goldenband, but a simpler way of looking at it is that you would naturally make a pause before each of the phrases in question. The reason for the pause would be the contrast.

In any case, the commas are not optional. Try saying them without a pause.

 

[Parla]

I also agree: the commas are obligatory. Please note that in each case, what follows the comma is an added thought: the sentences would still be complete sentences without those added phrases.

 

[goldenband]

I agree with Parla: the first part of each sentence is, essentially, a complete thought. What follows (after the comma) is commentary or contrast, but isn't strictly necessary to complete the thought. On the other hand, if one said --

I believe this may be a boring deed or an attractive pastime [depending on one's perspective].
I believe this animal may be a chicken or a turkey. [I'm not sure which]

-- then, in fact, you wouldn't need the comma, since the part that follows "or" is really a crucial part of the whole statement, and the whole loses integrity without it.

If there's a grammatical rule here, perhaps it relates to the completeness of the initial thought without the added element. But that's probably optimistic -- language is seldom so simple.

 

[Cagey]

Each of these sentences are is different and should have a separate thread.

You can find discussions of comma use by looking at: Comma thread portal with info, key word links and topic sentences
It will be useful to look it over and

In particular:

A search for comma such as will find discussions of threads that are similar to your first sentence.

This one is related to your third sentence: he was the one, not me. [comma speech tag]​

A general discussion of punctuation may be more helpful. I favor this website listed on our 'Resources' thread:

Punctuation
UK English, University of Sussex:
Guide to Punctuation

​

I am closing this thread. If you have further questions about any sentence in this thread, or about another sentence you come across, you are welcome to start a new thread to ask about. Please remember to give each sentence its own thread.

Cagey, moderator.