Ex 2:

1. As the teacher is sick, we'll have no class tomorrow.
2. She walked slowly because her leg was injured.
3. Mary looks happy because she has just got good marks .
4. Since it got dark, I couldn't read the leter.
5.As he came to the office 10 minutes, he missed the first bus.

Ex 3:

1. Mary didn't go to school because of her sickness .
2. I can't sleep because of the hot weather.
3. He left school because of his hard life.
4. The train was late because of the thick fog.
5.We're late for class because of the bad weather.

Ex 4:

1. We can't play soccer because the rain is heavy.
2. I didn't go to class on time because I got up late.
3. Because he is tired, he has to stay at home.
4. Because he worked hard, he passes all the exam.
5.They had to delay the soccer match because the weather was bad .

1 . Because of Mary's sickness , she didn't go to school yesterday 
2.  Because of the hot weather , i can't sleep
5. Because of the bad weather we are late 
4. the train was late because of the fog being thick