Thank you Gaieus for extensive answer.
I know about plugins for bezier's curves in SU.
But if I have prepared, complex pattern in .ai, and I don't have wish and time to redraw it?
I believe must be any variant.

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Please, somebody, HELP me, because I'd frustrated...

In Illustrator I have one, for example:

But when I have imported it in SU, like DWG, I have next:

How I can to get a smooth result?

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