I was unhappy because I had lost my watch.
My parents were tired because they had worked very hard.
My friend was nervous because he/she hadn't studied for the test.
We were excited because we had won a prize in a competition.
You were late because you had slept for a long time.
The teacher was angry because he/she...hadn't slept for a long time.
My parents were nervous because i had asked a difficult question.
(Вроде как там сказано составить столько предложений, на сколько мозгов хватит, но это мой максимум)