Put in was/wasn't/were/werent
1)Kate got married when she ... 24 years old
2)I phoned you yesterday evening but you ... at home. Where ... you
3)George ... at work last week because he ... ill. He'better now
4)The shops ... open yesterday because it ... a public holiday
5)... you at home at 9.30? No,I .... at work

От местоимения зависит, писать Was или were:
— was будет использоваться с местоимениями I, he, she, it.
— were будет использоваться с you, we, they.
Также это зависит от того, единственное это число или множественное. С единственным числом будет использоваться was, с множественным — were. _______________________________________________
1) Kate got married when she was 24 years old.
2) I phoned you yesterday evening but you weren't at home. Where were you?
3) George wasn't at work last week because he was ill. He's better now.
4) The shops weren't open yesterday because it was a public holiday.
5) Were you at home at 9.30? — No, I was at work.