The Spanish verbsir (to go) and ser (to be) share the same forms in the Preterite. The congugation of both verbs are shown below.

ir (full conjugation)

			

				
 
				
 
				
ir
			
			

				
yo
				
fui
				
(I went)
			
			

				
tú
				
fuiste
				
(you went)
			
			

				
Ud./él/ella
				
fue
				
(he went)
			
			

				
nosotros
				
fuimos
				
(we went)
			
			

				
vosotros
				
fuisteis
				
(you guys went)
			
			

				
Uds./ellos/ ellas
				
fueron
				
(you/they went)
			

ser (full conjugation)

			

				
 
				
 
				
ser
			
			

				
yo
				
fui
				
(I was)
			
			

				
tú
				
fuiste
				
(you were)
			
			

				
Ud./él/ella
				
fue
				
(he was)
			
			

				
nosotros
				
fuimos
				
(we were)
			
			

				
vosotros
				
fuisteis
				
(you guys were)
			
			

				
Uds./ellos/ ellas
				
fueron
				
(you/they were)
			

The context of a sentence or a conversation will let you know which verb is being used.

No fui yo, esta señora está confundida.
It wasn't I, this lady is confused.

Nunca fui a los toros.
I never went (to watch) the bullfight.

¿Con quién te fuiste al cine ayer?
With whom did you go to the movies yesterday?

Fuimos en bicicleta a Friburgo.
We went by bicycle to Fribourg (Switzerland).

Ustedes fueron muy imprudentes.
You were not careful.

¿Fueron ustedes a México?
Did you all go to Mexico?