Sure! Here are the sentences completed with suitable adjectives:

1. It was **disgraceful** of your friend to say bad things about you when you weren’t there.
2. Peter was in a terrible car accident last week. He’s **fortunate** to be alive.
3. She’s very **trustworthy**. She wouldn’t lie to you.
4. I couldn’t sleep because the bed was **uncomfortable**.
5. John’s very **active**. He goes running every evening.
6. His bedroom is always **messy** - he never puts anything away.
7. In many countries it’s **rude** to start eating before others are ready.
8. We should be **respectful** of people who have different cultures from us.

Let me know if you need more help!