If only...

I was watching the sitcom Friends these days, which is by the way one of my favorite sitcoms, and right at the begining of an episode I heard something that could be a great lesson for today's post. But first, let me give you some insight on what was going on before the expression came out. It started with Chandler and Monica talking about some trip they'd make in the upcoming weekend. The problem was that Rachel and Ross would be throwing their daughter's first birthday party in the same weekend as the trip and wouldn't let them miss it. Chandler, who was really looking forward to the trip, said ironically: If only she were one and had no idea what the hell a birthday was!

Chandler eventually gave in to the birthday, but what matters now is to know why he decided to use the expression If only in the beginning of his statement. If only is a very useful expression in English language because it can be used on a very regular basis. When you start a sentence with "If only", it means you wish something was different, or you're expressing regret about certain situations. For example: If only you were here / If only I had more money. If only I'd listened to you. Instead of saying "If only she were one and had no idea what the hell a birthday was!", Chandler could also have said "I wish she were one and had no idea what the hell a birthday was", but it is true that "If only" can be more emphatic. Both the expressions "If only" and "I wish" mean the same thing though. See how you can use them:

I wish I was taller.
I wish I knew the answer.
If only the sun would come out.
If only he could have explained!
Fonte: http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-5529.php