let me do it once before.

Hi,

let me do it once before. What do you mean? Before what?

once before = once as before = one time as before? Only 'once before' seems normal.

eg I did this once before. Now I'm going to do it again.

Best wishes, Clive

This is from Friends. I listen to it several times. It is exactly spoken like below, plus showned in the caption or footnote as below.

CliveHi,

let me do it once before. What do you mean? Before what?

once before = once as before = one time as before? Only 'once before' seems normal.

eg I did this

Hi,

If you are successful in learning to speak the way they do on 'Friends', then you too will be able to mystify many people with some of your English.

Thanks for this reminder. I will beware about this when watching Friends. In fact, for us having English as second language, we pretty much do not have judgement about what kind of English sounds normal in reality. That is the reason I or we ask questions here. This website is really helpful. Thanks.

CliveHi,

If you are successful in learning to speak the way they

Was this only part of the sentence? Or were they interrupted?

The only way I can think of using this phrase is when you continue to state the event you are doing something before.

Let me do it once before I have to go home. (in other words - I want a turn!)

Aha, I made a mistake. I am sorry about this.

The complete sentence should be:

YOU let me do it once before.

As Clive said, here I should understand "let" as "letted," then it makes sense. Right? Please confirm me.

BTW, so here once before means one time before. Right?

Chee

It means you allowed me (no such word as 'letted) me do it one time.

You allowed me to do it one time previously. (before this time)