How Can I Convert a 3D solidworks File to 3d AutoCad File

Hello Dear

How Can I Convert a 3D solidworks File to 3d AutoCad File???

Whenever I try to save any solid works file with .*acis extention..... this file is save as "Standard Acis Text File" & if we are import that file in Autocad So it shows in command box that Unable to read the File type.

what Shoul I do Now????

Please Help Me in my this Query needful....

Thanks

SolidworksImport export