11. Since people are always not satisfied with their present situation, they want further development.

　　改进: Since people are never satisfied with their status quo, they want further development.

　　12. The only thing they need to do is to find a job which can easily get big money.

　　改进: The only thing they need to do is to find a job that can bring them big money.

　　13. They like an active life but not a peaceful life.

　　改进: They like an active life rather than a peaceful one.