Réponse :
1. There has been two world wars.
2. There were big clouds in the sky.
3. There will be o motch on Soturday.
4. There has been no sunshine today.
5. There had been a concert the day before.
6. There was a lot of work to do.
7. There would be a quarrel if they both come.
8. There have been several complaints about your dog.
9. There were three men waiting for him outside.
10. There will be a party tonight.