1. He was trained very hard, so he could be a professional player 

Because......

2. It sonowed heavily, so we couldn't go on a picnic

Because........

2.He couldn't go to school because of his sickness

As...........

3.Peter was careless .He lost the game

Since.............

1. We decided to sell the house because of having a lot of difficulties.

Since...........

1.when

2. in case

3. since

4. unless

5. before

6. as long as

7. because

8. while

9. although

1.when

2. in case

3. since

4. unless

5. before

6. as long as

7. because

8. while

9. although