1, After David had gone home, we arrived
2, Before we took a look aruond the shops, we had lunch.
3, When we got out of the office, the light had gone uot.
4, By the time we stared our work, she had explained everything dearly.
5, Before my mother came home, my father had watered all the plants in the garden.
6, If you didn't behave yourself well, your parents wouldn't are happy
7, If people didn't throw rubbish in the street, it wouldn't look attractive
8, Unless she study hard, she won't pass the exam