1. He couldn't meet you because he is busy
2. Because of heavy rain, we can't go for a work
3. She couldn't come to the class because she is ill
4. Because the road is narrow, two cars can't pass each other
5. Because the test is difficult, nobody can do it
6. Since the source was pollutedmany people in this area feel unhealthy
8. I couldn't do the test because of it difficulty
9. Because of turning red of the traffic lights, we stopped the car
10. John succeeded in his extra brcause of working hard and methodically
11. I couldn't read the letter because it is dark
12. Because he has a good conduct, all the teachers love him