μὴ ἄλλως πως ἀποδεκτέον λεγομένης λόγων τέχνης;’
num alio modo ars orationum accipienda est
the commentary says that this is G abs and I have trouble understanding this. On the other hand, Brill Dictionary quotes this example as G dependent upon the verbal adjective, probably because the verb ἀποδέχομαι may take a G. I think the last would be a better explanation.