Question

En que situaciones se usa el was y were

Answer 1

El was y el were son el pasado del verbo to be que significa ser o estar y se usan con los siguientes pronombres:
I was, You were,He was, She was, It was, We were, You were, They were. Ejemplos:
I was here last week: Yo estuve aqui la semana pasada.
They were here last week: Ellos estuvieron aqui la semana pasada.
"was"corresponde a la primera persona del singular ("I") y a la tercera persona del singular (he,she,it) ; "were" se emplea para las demas personas 
I was - yo era,yo fui
you were - tu eras,tu fuiste, etc.
he/she/it was
we were
you were
they were
"Were" se emplea tambien para todas las personas del subjuntivo pasado: if were rich - si yo fuera ric; if were here - si el estuviera aqui. Sin embargo esta forma no se utiliza mucho en el ingles conversacional