Ago e back (informal) São usadas para falar de momentos passados no presente:
- I graduated from high school ten years ago.
(dez anos atrás)
- We sent the package three days ago.
(três dias atrás)
- I moved here about five years back.
(informal – cinco anos atrás)
Before e earlier são usados para descrever momentos passados em outro momento ainda no passado:
Aqui temos alguns exemplos:
- Yesterday I missed my train. I got to the train station at 7:10, but the train had left ten minutes before. (or ten minutes earlier/ ou dez minutos antes)
- I was very happy when I got this job last June, because I had lost my previous job six months before. (or six months earlier).
(= six months before last June/ seis meses antes do mês de junho que passou)
Diferença entre AGO, BACK, BEFORE e EARLIER