Find the mistake in the following sentences ,then write it correctly:

1. I couldn’t pretend the conference because I was busy .
2. Hydroelectric energy is probably the better form of renewable energy .
3. Pipes carry water from the roots to the leaves .
4. He wants to improve that he is a good teacher .
5. He used to participate in regularly sports trainings .
6. He looked very tired as he worked hard all day .
7. A wealthy man wanted to reword the people who helped him .
8. Could you tell me how old are you ?