7 Where ..... you yesterday, Sam? - I ..... at the zoo with my mum.

7. Where were you yesterday, Sam? - I was at the zoo with my mum.

В данном предложении необходимо использовать форму глагола to be (быть) в прошедшем времени. С местоимением "you" используем "were", а с местоимением "I" используем "was".

Ответ: Where were you yesterday, Sam? - I was at the zoo with my mum.