a) I WAS STUDYING english yesterday

b) They WERE PLAYING soccer at home

c) My friends WERE READING a book at school

d) You WERE EATING pizza last night

e) My mother WAS DRINKING

Explicação: Só observar qual verbo to be usar para cada pronome e entender que o past continuous se refere a ações que estavam ocorrendo no passado, sempre com o ING no final

Bons estudos!