1. Because I am sick, I do not go out
-> Because of my sickness, I do not go out.
2. Because the water is polluted, we can't swim in that river
-> Because of the polluted water, we can't swim in that river.
3. Because Nga has had a sore leg, she has difficulty in walking.
-> Because of a sore leg, she has difficulty in walking.
4. Because he behaved badly, he found himself in trouble.
-> Because of his bad behaviour, he found himself in trouble.
5. Because it was snowing, we didn't go out for a walk.
-> Because of snowing, we didn't go out for a walk.
6. Because of his good looks, he is popular with many girls.
-> Because he is good looking, he is popular with many girls.
7. Because of his serious sickness, he couldn't come to the class.
-> Because he has a serious sick, he couldn't come to the class.
8. Because of too much exhaust fume, people have to wear gauze masks in the street.
-> Because there is so much exhaust fume, people have to wear gauze masks in the street.
9. Because of their good performance, they won the first prize.
-> Because they performed well, they won the first prize.