Here are the appropriate words filled in the gaps:

1. **Because** his excellent performance, he received a promotion at work.
2. **Because** he had a flat tire, he arrived late to the meeting.
3. **Because** the weather was nice, they decided to go for a picnic.
4. The concert was canceled **because** the lead singer fell ill.
5. **Because of** the heavy traffic, they arrived late to the movie theater.
6. They couldn’t go on vacation **because of** their passports expired.
7. **Because** she’s allergic to peanuts, she avoids eating any food that contains them.
8. He didn’t want to go to the party **because** he had too much work to finish.
9. They missed the train **because** they overslept.
10. **Because of** the loud noise, the baby woke up from his nap.