"As" as a conjunction

[yo4561]

The GMAT All the Verbal book describes the use of "as" as a conjunction. An example of its use is below:
"Shannon ate her breakfast as she watched the news."

Would you ever need to use a comma when using "as" as a conjunction? I am assuming that you would never need to use a comma given that "as" is not included in "FANBOYS", but I just wanted to confirm my understanding. I also realize that there are bigger issues to pick at than commas on the GMAT

Thank you!

[esledge]

Yes, you would sometimes use a comma:

As she had a long day ahead of her, Shoshana ate breakfast.
Shoshana ate breakfast, as should we.

I'm not so sure what rule to apply for when to use the comma and when not to, so I think the takeaway is just not to eliminate choices based on the presence or lack of a comma with "as," since either might be right.