In the program Factor Fobia, Marley uses two words that are very similar sounding, atrás and tras.

Tuve un... hace unos meses atrás, me he ido a China.

I had a... some months ago, I've been to China.

Captions 28-29, Factor Fobia - Cucarachas

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As is evident, atrás can be used to indicate "ago," as in time past.

Yo empecé hace tres años atrás en el grupo Guamanique,

I started three years ago in the Guamanique group,

se llama Ballet Folklórico Guamanique, que es de Puerto Rico.

it's called the Guamanique Folk Ballet, which is from Puerto Rico.

Captions 3-4, Baile Folklórico de Puerto Rico - Los Bailarines

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Muchos años atrás, él fue general.
Many years ago, he was a general.

La última vez que nos vimos habrá sido unos seis años atrás.
Last time we met may have been some six years ago.

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Of course, atrás is also commonly used to indicate "backwards" or "towards the back."

Si eso era un primer paso, había sido un paso atrás.

If that was a first move, it had been a move backwards.

Caption 24, Los Años Maravillosos - Capítulo 2

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Ella fue atrás.
She went backwards.

Vaya hacia atrás, por favor.
Go backwards, please.