Import cad to rhino grasshoper

Hello, i am a very beginner from china. I was wondering is if i can import cad into rhino grasshopper.
i want to use grasshopper to build model automatically.
if i can import cad layer into grasshopper, such as road layer, it can make road poly line from cad to polygon.
building layer, it can make building poly-line from cad to polygon in rhino and there is index which i can control the high of different building(or it can give every building a random high)
sorry for my poor English.
thank you very much if you can give me some advice.