I couldn't answer the questions because I hadn't studied well.
I was angry because I hadn't passed my driving test.
I was pleased because I had passed my driving test.
I was tired because I had slept badly.
My father was (думаю, в учебнике ошибка и вместо is должно быть was) furious because I hadn't visited him for a long time.
My mother was worried because I hadn't eaten all day.