1, Kelvin disappointed because he had failed many times.

2, I was very hungry because I had not eaten anything for 24 hours

3, He ate all the fruits because they were ripe

4, He didn't go to sleep because he didn't finished the letter.

5, He was dismissed because he was late for work very often

6, He caused a serious accident because he drove very fast

7, There are not many people driving cars in this city because the streets are narrow

8, I couldn't do the test because it was so difficult

9, I have to have all my documet translated into Russian because I don't know Russian

10, The children went to school late because they had an accident