1. We haven't found a solution to our problem yet.
2. Have you ever participated in a challenging competition before?
3. I have successfully completed my project ahead of schedule.
4. They have maintained their partnership since they met.
   (Note: "fanned" seems to be incorrect; "maintained" or "strengthened" might be better depending on the context.)
5. I haven't seen any improvement in his behavior lately.
6. We haven't received any feedback on our proposal yet.
7. He has recently received an outstanding award for his contributions to the community.
8. Have you tried any other extreme sports, like skydiving?

1. We have not found a solution to the problem yet.

2. Have you ever participated in a challcnging competition before?

3. I have successfully completed my project ahead of schedule.

4. They have formed a harmonious partnership since they met.

5. I haven’t seen any improvement in his behavior lately.

6. We haven’t received any feedback on our proposal yet.

7. He has recently received an award for his outstanding contributions to the community.

8. Have you ever tried skydiving or any other extreme sports?