Curvilinear lines from DWG file aren't apparent on model using DRAPE command

The title says it all I guess, cuz I am asking it for a friend who’s trying to rush an assigment and have issues importing DWG file into her model. Culvilinears and circles are non-existent, we have no idea why. I really appreciate any help in advance, thank you.

I have to make it clear that I am not familiar with Sketch-Up, I am a person who just wants to help a friend in need.

Not realy.
In the title you wrote about the ‘Drape command’, and in the message about ‘issues importing DWG file into her model’, two different things.
What is the problem after all? What exactly do you want to do in SketchUp (besides helping your friend)?

I am really sorry for the inconvenience, using the drape command on the model that is imported from Autocad makes culvilinear lines disappear. That is the problem I am told.