Here are the sentences joined using appropriate connectors:

1. Henry needs to learn English, so I will teach him.

2. It was raining outside, so we went for a walk.

3. Jenny needs to ask me; I will buy it for her.

4. Yvonne played golf extremely well, although she was very young.

5. Franklin wants to get a new job because he is preparing for job interviews.

6. I'm writing a letter, and I'm leaving; you will find it tomorrow.

7. Marvin thinks he will buy the house, but he just wants to know what his wife thinks.

8. Cindy and David had breakfast before they left for work.

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

10. Alexander has been working sixty hours a week because there is an important presentation next week.