Ever been so tired..

That when you walk around, you close your eyes because it's like a little nap?

Grammar question LOL

a vs. an

a duck
an airplane
a book
an opinion
an email
a dog



a eulogy or an eulogy?
a UPS battery or an UPS battery?

The fate of an IM to a co-worker rests in your hands.




Seriously, this have been bothering me all day and I can't seem to google for the answer properly.