Some slippers may be boots. Some socks are not rubbers. Some rubbers are not slippers
No boot is a socks (E) + Some socks are slippers (I) ⇒ Some slippers are not boots (O*) ⇒ [Probable conclusion] ⇒ Some slippers may be boots(I). Some socks are slippers (I) + No slipper is a rubber (E) ⇒ Some socks are not rubbers (O). No slipper is a rubber (E) ⇒ conversion ⇒ Some rubbers are not slippers (O).