1. Math is complex but useful.

Question

2. Music is not only easy but also interesting.
3. Social studies is informative as well as interesting.
4. Music is not boring but exciting.
5. Technical arts is not only useful but also informative.
6. Chinese characters is annoying but helpful.

7. He is strong and humorous.
8. He is strict but witty.
9. She is attractive and well-teaching.
10. She is not ugly but charming.
11. She is not only gentle but also skillful.
12. He is handsome as well as fluent.
13. He is well-built but boring,
===============
Thank you for your help. Help me use correct and common expressions, please. Are the sentences all grammatical?

Answer 1

6. Chinese characters are annoying but helpful.

9. She is attractive and well educated.

12. He is handsome as well as fluent in Italian.

13 needs a period at the end, not a comma.

Everything else is fine.