can any one give hard drawing 3d models with dimensions to practice?
Good afternoon! You can search in google, and if you type the following word: drawings with dimensions, and you will find many drawings with dimensions, and after that you could do them in CATIA.
Hope my suggestion, help you to your question!
I found drawings I needed at: http://computeraideddesignguide.com/autocad-exercises/
Take a look. Good luck