1. The world is getting warmer. Polar bears are in danger of becoming extinct. (because)

Polar bears are in danger of becoming extinct because the world is getting warmer.

2. There weren't enough students. They closed the village school. (as)

They closed the village school as there weren't enough students.

3. I really enjoyed the concert. The music was too loud. (although)

I really enjoyed the concert although the music was too loud.

4. He got a creampie smashed in his face. Everyone laughed. (when)

Everyone laughed when he got a creampie smashed in his face.

5. Paul was walking to the bus stop. He found somebody's wallet on the ground. (while)

Paul found somebody's wallet on the ground while he was walking to the bus stop.

6. Jackie will take out the trash. She is done with her chores. (after)

Jackie will take out the trash after she is done with her chores.

7. You study for the test. You will do much better. (if)

If you study for the test, you will do much better.

8. Rex practiced his guitar. He could play the song perfectly. (until)

Rex practiced his guitar until he could play the song perfectly.